added data_type_traits for enums

# Conflicts:
#	demo/main.cpp

.gitignore

@@ -1,3 +1,4 @@
 .idea
 cmake-build-debug
 Testing
+debug

CMakeLists.txt

@@ -22,6 +22,10 @@ find_package(SQLite3 REQUIRED)
 find_package(PostgreSQL REQUIRED)
 find_package(MySQL REQUIRED)
 
+message(STATUS "Found ODBC config ${ODBC_CONFIG}")
+message(STATUS "Adding ODBC include directory: ${ODBC_INCLUDE_DIRS}")
+message(STATUS "Adding ODBC libs: ${ODBC_LIBRARIES}")
+
 message(STATUS "Found SQLite3 ${SQLite3_VERSION}")
 message(STATUS "Adding SQLite3 include directory: ${SQLite3_INCLUDE_DIRS}")
 message(STATUS "Adding SQLite3 libs: ${SQLite3_LIBRARIES}")

Todo.md

@@ -4,3 +4,44 @@
 - Read in entity fields
 - Add special handling for update in backends
 - Add ODBC/SQL Server backend
+
+
+Fetch eager strategies
+======================
+
+ONE TO ONE/MANY
+*person*             *address*
+- has one address    - belongs to person
+
+=> join "address" on "person.id" == "address.person_id"
+
+*address*             *person*
+- belongs to person   - has one address
+
+=> join "person" on "address.person_id" == "person.id"
+
+*book*               *author*
+- belongs to author  - has many books
+
+- => join "author" on "book.author_id" == "author.id"
+
+HAS MANY TO ONE (WITHOUT RELATION TABLE)
+
+*author*             *book*
+- has many books     - belongs to author
+
+- => join "book" on "author.id" == "book.author_id"
+
+if "has many" type has primary key & field "author_id"
+if table name belongs to entity template type?
+
+HAS MANY TO MANY (WITHOUT RELATION TABLE)
+
+*student*            *student_course*           *course*
+- has many courses   - belongs to student
+                     - belongs to course        - has many students
+
+=> join "student_course" on "student.id" == "student_course.student_id"
+   join "student_course" on "course.id" == "student_course.course_id"
+
+if has many type hasn't primary key (is relation table)

backends/mysql/include/mysql_connection.hpp

@@ -37,7 +37,7 @@ public:
 
   size_t execute(const std::string &stmt) override;
 
-  sql::record describe(const std::string& table) override;
+  std::vector<sql::column_definition> describe(const std::string& table) override;
 
   bool exists(const std::string &schema_name, const std::string &table_name) override;
 

backends/mysql/src/mysql_connection.cpp

@@ -181,13 +181,13 @@ std::unique_ptr<sql::query_result_impl> mysql_connection::fetch(const std::strin
 
   auto field_count = mysql_num_fields(result);
   auto fields = mysql_fetch_fields(result);
-  sql::record prototype;
+  std::vector<sql::column_definition> prototype;
   for (unsigned i = 0; i < field_count; ++i) {
     auto type = to_type(fields[i].type, fields[i].flags);
     auto options = to_constraints(fields[i].flags);
     auto null_opt = to_null_option(fields[i].flags);
 
-    prototype.append({fields[i].name, type, options, null_opt});
+    prototype.emplace_back(fields[i].name, type, options, null_opt);
   }
 
   return std::move(std::make_unique<sql::query_result_impl>(std::make_unique<mysql_result_reader>(result, field_count), std::move(prototype)));
@@ -216,7 +216,7 @@ size_t mysql_connection::execute(const std::string &stmt)
   return mysql_affected_rows(mysql_.get());
 }
 
-sql::record mysql_connection::describe(const std::string &table)
+std::vector<sql::column_definition> mysql_connection::describe(const std::string &table)
 {
   std::string stmt("SHOW COLUMNS FROM " + table);
 
@@ -230,7 +230,7 @@ sql::record mysql_connection::describe(const std::string &table)
   }
 
   mysql_result_reader reader(result, mysql_num_fields(result));
-  sql::record prototype;
+  std::vector<sql::column_definition> prototype;
   while (reader.fetch()) {
 
     char *end = nullptr;
@@ -242,7 +242,7 @@ sql::record mysql_connection::describe(const std::string &table)
     if (strtoul(reader.column(2), &end, 10) == 0) {
       null_opt = sql::null_option::NOT_NULL;
     }
-    prototype.append({name, typeinfo.type, {typeinfo.size}, null_opt, prototype.size()});
+    prototype.push_back({name, typeinfo.type, {typeinfo.size}, null_opt, prototype.size()});
   }
 
   return prototype;

backends/mysql/test/CMakeLists.txt

@@ -3,7 +3,7 @@ Include(FetchContent)
 FetchContent_Declare(
   Catch2
   GIT_REPOSITORY https://github.com/catchorg/Catch2.git
-  GIT_TAG        v3.4.0 # or a later release
+  GIT_TAG        v3.5.4 # or a later release
 )
 
 FetchContent_MakeAvailable(Catch2)

backends/postgres/include/postgres_connection.hpp

@@ -33,7 +33,7 @@ public:
 
   size_t execute(const std::string &stmt) override;
 
-  sql::record describe(const std::string& table) override;
+  std::vector<sql::column_definition> describe(const std::string& table) override;
 
   bool exists(const std::string &schema_name, const std::string &table_name) override;
 

backends/postgres/src/postgres_connection.cpp

@@ -51,14 +51,13 @@ std::unique_ptr<sql::query_result_impl> postgres_connection::fetch(const std::st
 
   throw_postgres_error(res, conn_, "postgres", stmt);
 
-  sql::record prototype;
+  std::vector<sql::column_definition> prototype;
   auto num_col = PQnfields(res);
   for (int i = 0; i < num_col; ++i) {
     const char *col_name = PQfname(res, i);
     auto type = PQftype(res, i);
     auto size = PQfmod(res, i);
-//    std::cout << "column " << col_name << ", type " << type << " (size: " << size << ")\n";
+    prototype.emplace_back(col_name);
-    prototype.append(sql::column_definition{col_name});
   }
   return std::move(std::make_unique<sql::query_result_impl>(std::make_unique<postgres_result_reader>(res), std::move(prototype)));
 }
@@ -131,7 +130,7 @@ sql::data_type_t string2type(const char *type)
   }
 }
 
-sql::record postgres_connection::describe(const std::string &table)
+std::vector<sql::column_definition> postgres_connection::describe(const std::string &table)
 {
   std::string stmt(
     "SELECT ordinal_position, column_name, udt_name, data_type, is_nullable, column_default FROM information_schema.columns WHERE table_schema='public' AND table_name='" + table + "'");
@@ -141,7 +140,7 @@ sql::record postgres_connection::describe(const std::string &table)
   throw_postgres_error(res, conn_, "postgres", stmt);
 
   postgres_result_reader reader(res);
-  sql::record prototype;
+  std::vector<sql::column_definition> prototype;
   while (reader.fetch()) {
     char *end = nullptr;
     // Todo: Handle error
@@ -156,7 +155,7 @@ sql::record postgres_connection::describe(const std::string &table)
       null_opt = sql::null_option::NOT_NULL;
     }
     // f.default_value(res->column(4));
-    prototype.append({name, type, utils::null_attributes, null_opt, index});
+    prototype.emplace_back(name, type, utils::null_attributes, null_opt, index);
   }
 
   return std::move(prototype);

backends/postgres/test/CMakeLists.txt

@@ -3,7 +3,7 @@ Include(FetchContent)
 FetchContent_Declare(
   Catch2
   GIT_REPOSITORY https://github.com/catchorg/Catch2.git
-  GIT_TAG        v3.4.0 # or a later release
+  GIT_TAG        v3.5.4 # or a later release
 )
 
 FetchContent_MakeAvailable(Catch2)
@@ -12,14 +12,13 @@ list(APPEND CMAKE_MODULE_PATH ${catch2_SOURCE_DIR}/extras)
 include(CTest)
 include(Catch)
 
-set(POSTGRES_CONNECTION_STRING "postgres://test:test123@127.0.0.1:5432/matador_test")
+set(POSTGRES_CONNECTION_STRING "postgres://test:test123@127.0.0.1:15432/test")
 
 configure_file(Connection.hpp.in ${PROJECT_BINARY_DIR}/backends/postgres/test/connection.hpp @ONLY IMMEDIATE)
 
 message(STATUS "postgresql connection string: ${POSTGRES_CONNECTION_STRING}")
 
 set(TEST_SOURCES
-  ../../tests/QueryTest.cpp
   ../../tests/QueryTest.cpp
   ../../tests/ConnectionTest.cpp
   ../../tests/QueryRecordTest.cpp

backends/sqlite/include/sqlite_connection.hpp

@@ -33,14 +33,14 @@ public:
 
   size_t execute(const std::string &stmt) override;
 
-  sql::record describe(const std::string& table) override;
+  std::vector<sql::column_definition> describe(const std::string& table) override;
 
   bool exists(const std::string &schema_name, const std::string &table_name) override;
 
 private:
   struct fetch_context
   {
-    sql::record prototype;
+    std::vector<sql::column_definition> prototype;
     sqlite_result_reader::rows rows;
   };
 

backends/sqlite/include/sqlite_prepared_result_reader.hpp

@@ -32,7 +32,7 @@ public:
   void read_value(const char *id, size_t index, char *value, size_t s) override;
   void read_value(const char *id, size_t index, std::string &value) override;
   void read_value(const char *id, size_t index, std::string &value, size_t s) override;
-  void read_value(const char *id, size_t index, sql::any_type &value, sql::data_type_t type, size_t size) override;
+  void read_value(const char *id, size_t index, sql::value &val, size_t size) override;
 
 private:
   sqlite3 *db_{nullptr};

backends/sqlite/src/sqlite_connection.cpp

@@ -65,7 +65,7 @@ int sqlite_connection::parse_result(void* param, int column_count, char** values
 
   if (context->prototype.empty()) {
     for(int i = 0; i < column_count; ++i) {
-      context->prototype.append(sql::column_definition{columns[i]});
+      context->prototype.emplace_back(columns[i]);
     }
   }
 
@@ -144,12 +144,12 @@ sql::data_type_t string2type(const char *type)
   }
 }
 
-sql::record sqlite_connection::describe(const std::string& table)
+std::vector<sql::column_definition> sqlite_connection::describe(const std::string& table)
 {
   const auto result = fetch_internal("PRAGMA table_info(" + table + ")");
 
   sqlite_result_reader reader(result.rows, result.prototype.size());
-  sql::record prototype;
+  std::vector<sql::column_definition> prototype;
   while (reader.fetch()) {
     char *end = nullptr;
     // Todo: add index to column
@@ -163,7 +163,7 @@ sql::record sqlite_connection::describe(const std::string& table)
       null_opt = sql::null_option::NOT_NULL;
     }
     // f.default_value(res->column(4));
-    prototype.append({name, type, utils::null_attributes, null_opt, index});
+    prototype.emplace_back(name, type, utils::null_attributes, null_opt, index);
   }
 
   return std::move(prototype);

backends/sqlite/src/sqlite_prepared_result_reader.cpp

@@ -107,8 +107,8 @@ void sqlite_prepared_result_reader::read_value(const char *id, size_t index, std
   query_result_reader::read_value(id, index, value, s);
 }
 
-void sqlite_prepared_result_reader::read_value(const char *id, size_t index, sql::any_type &value, sql::data_type_t type, size_t size)
+void sqlite_prepared_result_reader::read_value(const char *id, size_t index, sql::value &val, size_t size)
 {
-  query_result_reader::read_value(id, index, value, type, size);
+  query_result_reader::read_value(id, index, val, size);
 }
 }

backends/sqlite/test/CMakeLists.txt

@@ -3,7 +3,7 @@ Include(FetchContent)
 FetchContent_Declare(
   Catch2
   GIT_REPOSITORY https://github.com/catchorg/Catch2.git
-  GIT_TAG        v3.4.0 # or a later release
+  GIT_TAG        v3.5.4 # or a later release
 )
 
 FetchContent_MakeAvailable(Catch2)

backends/tests/QueryRecordTest.cpp

@@ -206,13 +206,13 @@ TEST_CASE_METHOD(QueryRecordFixture, "Execute update record statement", "[sessio
   for (const auto &i: result) {
     REQUIRE(i.size() == 3);
     REQUIRE(i.at(0).name() == "id");
-    REQUIRE(i.at(0).type() == data_type_t::type_long_long);
+    REQUIRE(i.at(0).is_integer());
     REQUIRE(i.at(0).as<long long>() == 7);
     REQUIRE(i.at(1).name() == "name");
-    REQUIRE(i.at(1).type() == data_type_t::type_varchar);
+    REQUIRE(i.at(1).is_varchar());
     REQUIRE(i.at(1).as<std::string>() == "jane");
     REQUIRE(i.at(2).name() == "age");
-    REQUIRE(i.at(2).type() == matador::sql::data_type_t::type_int);
+    REQUIRE(i.at(2).is_integer());
     REQUIRE(i.at(2).as<int>() == 35);
   }
 
@@ -252,7 +252,8 @@ TEST_CASE_METHOD(QueryRecordFixture, "Execute select statement", "[session][reco
   auto rec = db.query(schema).select({"id", "name", "age"})
   .from("person")
   .fetch_one();
-  REQUIRE(rec.at(1).str() == "george");
+  REQUIRE(rec.has_value());
+  REQUIRE(rec->at(1).str() == "george");
 
   auto name = db.query(schema).select({"name"})
   .from("person")
@@ -386,15 +387,16 @@ TEST_CASE_METHOD(QueryRecordFixture, "Test quoted identifier", "[session][record
 
   auto res = db.query(schema).select({"from", "to"}).from("quotes").fetch_one();
 
-  REQUIRE("Berlin" == res.at("from").str());
+  REQUIRE(res.has_value());
-  REQUIRE("London" == res.at("to").str());
+  REQUIRE("Berlin" == res->at("from").str());
+  REQUIRE("London" == res->at("to").str());
 
   db.query(schema).update("quotes").set({{"from", "Hamburg"}, {"to", "New York"}}).where("from"_col == "Berlin").execute();
 
   res = db.query(schema).select({"from", "to"}).from("quotes").fetch_one();
 
-  REQUIRE("Hamburg" == res.at("from").str());
+  REQUIRE("Hamburg" == res->at("from").str());
-  REQUIRE("New York" == res.at("to").str());
+  REQUIRE("New York" == res->at("to").str());
 
   db.query(schema).drop().table("quotes").execute();
 }

backends/tests/QueryTest.cpp

@@ -10,6 +10,9 @@
 #include "models/airplane.hpp"
 #include "models/flight.hpp"
 #include "models/person.hpp"
+#include "models/recipe.hpp"
+
+#include <iostream>
 
 using namespace matador::sql;
 using namespace matador::test;
@@ -29,6 +32,9 @@ public:
     drop_table_if_exists("flight");
     drop_table_if_exists("airplane");
     drop_table_if_exists("person");
+    drop_table_if_exists("recipe_ingredients");
+    drop_table_if_exists("recipes");
+    drop_table_if_exists("ingredients");
   }
 
 protected:
@@ -79,13 +85,14 @@ TEST_CASE_METHOD(QueryFixture, "Execute select statement with where clause", "[s
 
   auto res = db.query(schema)
   .insert()
-  .into<person>("person")
+  .into("person", column_generator::generate<person>(schema, true))
   .values(george)
   .execute();
   REQUIRE(res == 1);
 
   // fetch person as record
-  auto result_record = db.query(schema).select<person>()
+  auto result_record = db.query(schema)
+    .select(column_generator::generate<person>(schema, true))
     .from("person")
     .where("id"_col == 7)
     .fetch_all();
@@ -93,18 +100,19 @@ TEST_CASE_METHOD(QueryFixture, "Execute select statement with where clause", "[s
   for (const auto &i: result_record) {
     REQUIRE(i.size() == 4);
     REQUIRE(i.at(0).name() == "id");
-    REQUIRE(i.at(0).type() == data_type_t::type_long_long);
+    REQUIRE(i.at(0).is_integer());
     REQUIRE(i.at(0).as<long long>() == george.id);
     REQUIRE(i.at(1).name() == "name");
-    REQUIRE(i.at(1).type() == data_type_t::type_varchar);
+    REQUIRE(i.at(1).is_varchar());
     REQUIRE(i.at(1).as<std::string>() == george.name);
     REQUIRE(i.at(2).name() == "age");
-    REQUIRE(i.at(2).type() == matador::sql::data_type_t::type_long_long);
+    REQUIRE(i.at(2).is_integer());
     REQUIRE(i.at(2).as<long long>() == george.age);
   }
 
   // fetch person as person
-  auto result_person = db.query(schema).select<person>()
+  auto result_person = db.query(schema)
+    .select(column_generator::generate<person>(schema, true))
     .from("person")
     .where("id"_col == 7)
     .fetch_all<person>();
@@ -144,13 +152,13 @@ TEST_CASE_METHOD(QueryFixture, "Execute insert statement", "[session]")
   for (const auto &i: result_record) {
     REQUIRE(i.size() == 3);
     REQUIRE(i.at(0).name() == "id");
-    REQUIRE(i.at(0).type() == data_type_t::type_long_long);
+    REQUIRE(i.at(0).is_integer());
     REQUIRE(i.at(0).as<unsigned long>() == 7);
     REQUIRE(i.at(1).name() == "name");
-    REQUIRE(i.at(1).type() == data_type_t::type_varchar);
+    REQUIRE(i.at(1).is_varchar());
     REQUIRE(i.at(1).as<std::string>() == "george");
     REQUIRE(i.at(2).name() == "color");
-    REQUIRE(i.at(2).type() == matador::sql::data_type_t::type_varchar);
+    REQUIRE(i.at(2).is_varchar());
     REQUIRE(i.at(2).as<std::string>() == "green");
   }
 
@@ -176,23 +184,36 @@ TEST_CASE_METHOD(QueryFixture, "Select statement with foreign key", "[session]")
   };
 
   for (const auto &plane: planes) {
-    auto res = db.query(schema).insert().into<airplane>("airplane").values(*plane).execute();
+    auto res = db.query(schema)
+      .insert()
+      .into("airplane", column_generator::generate<airplane>(schema, true))
+      .values(*plane)
+      .execute();
     REQUIRE(res == 1);
   }
 
-  auto count = db.query(schema).select({count_all()}).from("airplane").fetch_value<int>();
+  auto count = db.query(schema)
+    .select({count_all()})
+    .from("airplane")
+    .fetch_value<int>().value();
   REQUIRE(count == 3);
 
   flight f4711{4, planes.at(1), "hans"};
 
-  auto res = db.query(schema).insert().into<flight>("flight").values(f4711).execute();
+  auto res = db.query(schema)
+    .insert()
+    .into("flight", column_generator::generate<flight>(schema, true))
+    .values(f4711)
+    .execute();
   REQUIRE(res == 1);
 
-  auto f = *db.query(schema).select<flight>().from("flight").fetch_all<flight>().begin();
+  auto f = *db.query(schema)
-  REQUIRE(f.id == 4);
+    .select(column_generator::generate<flight>(schema, true))
-  REQUIRE(f.pilot_name == "hans");
+    .from("flight")
-  REQUIRE(f.airplane.get() != nullptr);
+    .fetch_all().begin();
-  REQUIRE(f.airplane->id == 2);
+  REQUIRE(f.at(0).as<unsigned long>() == 4);
+  REQUIRE(f.at(1).as<unsigned long>() == 2);
+  REQUIRE(f.at(2).as<std::string>() == "hans");
 
   db.query(schema).drop().table("flight").execute();
   db.query(schema).drop().table("airplane").execute();
@@ -217,11 +238,18 @@ TEST_CASE_METHOD(QueryFixture, "Select statement with foreign key and join_left"
   };
 
   for (const auto &plane: planes) {
-    auto res = db.query(schema).insert().into<airplane>("airplane").values(*plane).execute();
+    auto res = db.query(schema)
+      .insert()
+      .into("airplane", column_generator::generate<airplane>(schema, true))
+      .values(*plane)
+      .execute();
     REQUIRE(res == 1);
   }
 
-  auto count = db.query(schema).select({count_all()}).from("airplane").fetch_value<int>();
+  auto count = db.query(schema)
+    .select({count_all()})
+    .from("airplane")
+    .fetch_value<int>().value();
   REQUIRE(count == 3);
 
   std::vector<entity<flight>> flights{
@@ -232,15 +260,21 @@ TEST_CASE_METHOD(QueryFixture, "Select statement with foreign key and join_left"
   };
 
   for (const auto &f: flights) {
-    auto res = db.query(schema).insert().into<flight>("flight").values(*f).execute();
+    auto res = db.query(schema)
+      .insert()
+      .into("flight", {"id", "airplane_id", "pilot_name"})
+      .values(*f)
+      .execute();
     REQUIRE(res == 1);
   }
 
-  auto f = *db.query(schema).select<flight>().from("flight").fetch_all<flight>().begin();
+  auto f = *db.query(schema)
-  REQUIRE(f.id == 4);
+    .select(column_generator::generate<flight>(schema, true))
-  REQUIRE(f.pilot_name == "hans");
+    .from("flight")
-  REQUIRE(f.airplane.get() != nullptr);
+    .fetch_all().begin();
-  REQUIRE(f.airplane->id == 1);
+  REQUIRE(f.at(0).as<unsigned long>() == 4);
+  REQUIRE(f.at(1).as<unsigned long>() == 1);
+  REQUIRE(f.at(2).as<std::string>() == "hans");
 
   auto result = db.query(schema).select({"f.id", "ap.brand", "ap.model", "f.pilot_name"})
     .from({"flight", "f"})
@@ -264,5 +298,238 @@ TEST_CASE_METHOD(QueryFixture, "Select statement with foreign key and join_left"
 
   db.query(schema).drop().table("flight").execute();
   db.query(schema).drop().table("airplane").execute();
+}
 
+TEST_CASE_METHOD(QueryFixture, "Select statement with foreign key and for single entity", "[session][join_left][find]") {
+  schema.attach<airplane>("airplane");
+  schema.attach<flight>("flight");
+  db.query(schema).create()
+  .table<airplane>("airplane")
+  .execute();
+
+  db.query(schema).create()
+  .table<flight>("flight")
+  .execute();
+
+  std::vector<entity<airplane>> planes{
+  make_entity<airplane>(1, "Airbus", "A380"),
+  make_entity<airplane>(2, "Boeing", "707"),
+  make_entity<airplane>(3, "Boeing", "747")
+  };
+
+  for (const auto &plane: planes) {
+    auto res = db
+      .query(schema)
+      .insert()
+      .into("airplane", column_generator::generate<airplane>(schema, true))
+      .values(*plane)
+      .execute();
+    REQUIRE(res == 1);
+  }
+
+  auto count = db
+    .query(schema)
+    .select({count_all()})
+    .from("airplane")
+    .fetch_value<int>().value();
+  REQUIRE(count == 3);
+
+  std::vector<entity<flight>> flights{
+  make_entity<flight>(4, planes.at(0), "hans"),
+  make_entity<flight>(5, planes.at(0), "otto"),
+  make_entity<flight>(6, planes.at(1), "george"),
+  make_entity<flight>(7, planes.at(2), "paul")
+  };
+
+  for (const auto &f: flights) {
+    auto res = db.query(schema)
+      .insert()
+      .into("flight", column_generator::generate<flight>(schema, true))
+      .values(*f)
+      .execute();
+    REQUIRE(res == 1);
+  }
+
+  auto f = db.query(schema)
+    .select(column_generator::generate<flight>(schema, true))
+    .from("flight")
+    .fetch_one();
+  REQUIRE(f.has_value());
+  REQUIRE(f->at(0).as<unsigned long>() == 4);
+  REQUIRE(f->at(1).as<unsigned long>() == 1);
+  REQUIRE(f->at(2).as<std::string>() == "hans");
+
+  auto result = db
+    .query(schema)
+    .select({"f.id", "f.airplane_id", "ap.brand", "ap.model", "f.pilot_name"})
+    .from({"flight", "f"})
+    .join_left({"airplane", "ap"})
+    .on("f.airplane_id"_col == "ap.id"_col)
+    .where("f.id"_col == 4)
+    .fetch_one<flight>();
+
+  auto expected_flight = flights[0];
+
+  REQUIRE(result);
+  REQUIRE(result->id == expected_flight->id);
+  REQUIRE(result->pilot_name == expected_flight->pilot_name);
+  REQUIRE(result->airplane.get());
+  REQUIRE(result->airplane->id == 1);
+  REQUIRE(result->airplane->model == "A380");
+  REQUIRE(result->airplane->brand == "Airbus");
+
+  db.query(schema).drop().table("flight").execute();
+  db.query(schema).drop().table("airplane").execute();
+}
+
+TEST_CASE_METHOD(QueryFixture, "Select statement with many to many relationship", "[session][join][many_to_many]") {
+  schema.attach<recipe>("recipes");
+  schema.attach<ingredient>("ingredients");
+  schema.attach<recipe_ingredient>("recipe_ingredients");
+  db.query(schema).create()
+  .table<recipe>("recipes")
+  .execute();
+
+  db.query(schema).create()
+  .table<ingredient>("ingredients")
+  .execute();
+
+  db.query(schema).create()
+  .table<recipe_ingredient>("recipe_ingredients")
+  .execute();
+
+  std::vector<ingredient> ingredients {
+    {1, "Apple"},
+    {2, "Strawberry"},
+    {3, "Pineapple"},
+    {4, "Sugar"},
+    {5, "Flour"},
+    {6, "Butter"},
+    {7, "Beans"}
+  };
+
+  for (const auto &i: ingredients) {
+    auto res = db
+    .query(schema)
+    .insert()
+    .into("ingredients", column_generator::generate<ingredient>(schema, true))
+    .values(i)
+    .execute();
+    REQUIRE(res == 1);
+  }
+
+  std::vector<recipe> recipes{
+    {7, "Apple Crumble"},
+    {8, "Beans Chili"},
+    {9, "Fruit Salad"}
+  };
+
+  for (const auto &r: recipes) {
+    auto res = db
+    .query(schema)
+    .insert()
+    .into("recipes", column_generator::generate<recipe>(schema, true))
+    .values(r)
+    .execute();
+    REQUIRE(res == 1);
+  }
+
+  std::vector<std::pair<int, int>> recipe_ingredients {
+    { 7, 1 },
+    { 7, 4 },
+    { 7, 5 },
+    { 8, 6 },
+    { 8, 7 },
+    { 9, 1 },
+    { 9, 2 },
+    { 9, 3 }
+  };
+
+  for (const auto &ri: recipe_ingredients) {
+    auto res = db
+    .query(schema)
+    .insert()
+    .into("recipe_ingredients", column_generator::generate<recipe_ingredient>(schema, true))
+    .values({ri.first, ri.second})
+    .execute();
+    REQUIRE(res == 1);
+  }
+
+  auto result = db
+    .query(schema)
+    .select({"r.id", "r.name", "ri.ingredient_id"})
+    .from({"recipes", "r"})
+    .join_left({"recipe_ingredients", "ri"})
+    .on("r.id"_col == "ri.recipe_id"_col)
+    .fetch_all();
+
+  std::vector<std::tuple<unsigned long, std::string, unsigned long>> expected_result_one_join {
+    {7, "Apple Crumble", 1},
+    {7, "Apple Crumble", 4},
+    {7, "Apple Crumble", 5},
+    {8, "Beans Chili", 6},
+    {8, "Beans Chili", 7},
+    {9, "Fruit Salad", 1},
+    {9, "Fruit Salad", 2},
+    {9, "Fruit Salad", 3}
+  };
+  size_t index{0};
+  for (const auto &r: result) {
+    REQUIRE(r.size() == 3);
+    REQUIRE(r.at(0).as<unsigned long>().value() == std::get<0>(expected_result_one_join[index]));
+    REQUIRE(r.at(1).as<std::string>().value() == std::get<1>(expected_result_one_join[index]));
+    REQUIRE(r.at(2).as<unsigned long>().value() == std::get<2>(expected_result_one_join[index]));
+    ++index;
+  }
+
+  result = db
+  .query(schema)
+  .select({"r.id", "r.name", "ri.ingredient_id", "i.name"})
+  .from({"recipes", "r"})
+  .join_left({"recipe_ingredients", "ri"}).on("r.id"_col == "ri.recipe_id"_col)
+  .join_left({"ingredients", "i"}).on("ri.ingredient_id"_col == "i.id"_col)
+  .fetch_all();
+
+  std::vector<std::tuple<unsigned long, std::string, unsigned long, std::string>> expected_result_two_joins {
+    {7, "Apple Crumble", 1, "Apple"},
+    {7, "Apple Crumble", 4, "Sugar"},
+    {7, "Apple Crumble", 5, "Flour"},
+    {8, "Beans Chili", 6, "Butter"},
+    {8, "Beans Chili", 7, "Beans"},
+    {9, "Fruit Salad", 1, "Apple"},
+    {9, "Fruit Salad", 2, "Strawberry"},
+    {9, "Fruit Salad", 3, "Pineapple"}
+  };
+  index = 0;
+  for (const auto &r: result) {
+    REQUIRE(r.size() == 4);
+    REQUIRE(r.at(0).as<unsigned long>().value() == std::get<0>(expected_result_two_joins[index]));
+    REQUIRE(r.at(1).as<std::string>().value() == std::get<1>(expected_result_two_joins[index]));
+    REQUIRE(r.at(2).as<unsigned long>().value() == std::get<2>(expected_result_two_joins[index]));
+    REQUIRE(r.at(3).as<std::string>().value() == std::get<3>(expected_result_two_joins[index]));
+    ++index;
+  }
+
+  result = db
+  .query(schema)
+  .select({"r.id", "r.name", "ri.ingredient_id", "i.name"})
+  .from({"recipes", "r"})
+  .join_left({"recipe_ingredients", "ri"}).on("r.id"_col == "ri.recipe_id"_col)
+  .join_left({"ingredients", "i"}).on("ri.ingredient_id"_col == "i.id"_col)
+  .where("r.id"_col == 8)
+  .fetch_all();
+
+  index = 3;
+  for (const auto &r: result) {
+    REQUIRE(r.size() == 4);
+    REQUIRE(r.at(0).as<unsigned long>().value() == std::get<0>(expected_result_two_joins[index]));
+    REQUIRE(r.at(1).as<std::string>().value() == std::get<1>(expected_result_two_joins[index]));
+    REQUIRE(r.at(2).as<unsigned long>().value() == std::get<2>(expected_result_two_joins[index]));
+    REQUIRE(r.at(3).as<std::string>().value() == std::get<3>(expected_result_two_joins[index]));
+    ++index;
+  }
+
+  db.query(schema).drop().table("recipe_ingredients").execute();
+  db.query(schema).drop().table("recipes").execute();
+  db.query(schema).drop().table("ingredients").execute();
 }

backends/tests/SessionTest.cpp

@@ -5,6 +5,7 @@
 #include "matador/sql/session.hpp"
 
 #include "models/airplane.hpp"
+#include "models/flight.hpp"
 
 class SessionFixture
 {
@@ -16,9 +17,8 @@ public:
 
   ~SessionFixture()
   {
-    drop_table_if_exists("flight");
+    drop_table_if_exists("flights");
-    drop_table_if_exists("airplane");
+    drop_table_if_exists("airplanes");
-    drop_table_if_exists("person");
   }
 
 protected:
@@ -37,10 +37,63 @@ private:
 using namespace matador;
 
 TEST_CASE_METHOD(SessionFixture, "Session relation test", "[session][relation]") {
-
+  using namespace matador;
-  ses.attach<matador::test::airplane>("airplane");
+  ses.attach<test::airplane>("airplanes");
+  ses.attach<test::flight>("flights");
   ses.create_schema();
-  ses.insert<test::airplane>(1, "Boeing", "A380");
+  auto plane = ses.insert<test::airplane>(1, "Boeing", "A380");
+  auto f = ses.insert<test::flight>(2, plane, "sully");
+
+  auto result = ses.find<test::flight>(2);
+  REQUIRE(result.is_ok());
+}
+
+TEST_CASE_METHOD(SessionFixture, "Use session to find object with id", "[session][find]") {
+  using namespace matador::test;
+  ses.attach<airplane>("airplanes");
+  ses.create_schema();
+  auto a380 = ses.insert<airplane>(1, "Boeing", "A380");
+
+  auto result = ses.find<airplane>(2);
+  REQUIRE(!result.is_ok());
+  REQUIRE((result.err() == sql::session_error::FailedToFindObject));
+
+  result = ses.find<airplane>(1);
+
+  REQUIRE(result);
+  auto read_a380 = result.value();
+  REQUIRE(a380->id == read_a380->id);
+}
+
+TEST_CASE_METHOD(SessionFixture, "Use session to find all objects", "[session][find]") {
+  using namespace matador::test;
+  ses.attach<airplane>("airplanes");
+  ses.create_schema();
+
+  std::vector<std::unique_ptr<airplane>> planes;
+  planes.emplace_back(new airplane(1, "Airbus", "A380"));
+  planes.emplace_back(new airplane(2, "Boeing", "707"));
+  planes.emplace_back(new airplane(3, "Boeing", "747"));
+
+  for (auto &&plane: planes) {
+    ses.insert(plane.release());
+  }
+
+  auto result = ses.find<airplane>();
+
+  std::vector<std::tuple<int, std::string, std::string>> expected_result {
+    {1, "Airbus", "A380"},
+    {2, "Boeing", "707"},
+    {3, "Boeing", "747"}
+  };
+  REQUIRE(result);
+  auto all_planes = result.release();
+  size_t index {0};
+  for (const auto &i: all_planes) {
+    REQUIRE(i.id == std::get<0>(expected_result[index]));
+    REQUIRE(i.brand == std::get<1>(expected_result[index]));
+    REQUIRE(i.model == std::get<2>(expected_result[index]));
+    ++index;
+  }
 
-  REQUIRE(true);
 }

backends/tests/StatementTest.cpp

@@ -52,7 +52,7 @@ TEST_CASE_METHOD(StatementTestFixture, "Create prepared statement", "[statement]
   table ap{"airplane"};
   SECTION("Insert with prepared statement and placeholder") {
     auto stmt = db.query(schema).insert()
-    .into<airplane>("airplane")
+    .into("airplane", column_generator::generate<airplane>(schema, true))
     .values<airplane>()
     .prepare();
 
@@ -62,7 +62,10 @@ TEST_CASE_METHOD(StatementTestFixture, "Create prepared statement", "[statement]
       stmt.reset();
     }
 
-    auto result = db.query(schema).select<airplane>().from(ap).fetch_all<airplane>();
+    auto result = db.query(schema)
+      .select(column_generator::generate<airplane>(schema, true))
+      .from(ap)
+      .fetch_all<airplane>();
 
     size_t index{0};
     for (const auto &i: result) {
@@ -74,11 +77,19 @@ TEST_CASE_METHOD(StatementTestFixture, "Create prepared statement", "[statement]
 
   SECTION("Select with prepared statement") {
     for (const auto &plane: planes) {
-      auto res = db.query(schema).insert().into<airplane>("airplane").values(*plane).execute();
+      auto res = db.query(schema)
+        .insert()
+        .into("airplane", column_generator::generate<airplane>(schema, true))
+        .values(*plane)
+        .execute();
       REQUIRE(res == 1);
     }
 
-    auto stmt = db.query(schema).select<airplane>().from(ap).where("brand"_col == _).prepare();
+    auto stmt = db.query(schema)
+      .select(column_generator::generate<airplane>(schema, true))
+      .from(ap)
+      .where("brand"_col == _)
+      .prepare();
 
     stmt.bind(0, "Airbus");
 

backends/tests/TypeTraitsTest.cpp

@@ -1,6 +1,7 @@
 #include <catch2/catch_test_macros.hpp>
 
 #include "matador/sql/connection.hpp"
+#include "matador/sql/column_generator.hpp"
 
 #include "matador/utils/enum_mapper.hpp"
 
@@ -8,6 +9,7 @@
 
 #include "models/location.hpp"
 
+using namespace matador::sql;
 using namespace matador::test;
 
 class TypeTraitsTestFixture
@@ -50,10 +52,8 @@ static const matador::utils::enum_mapper<Color> color_enum({
                                                            {Color::Brown,  "brown"}
                                                            });
 
-namespace matador::sql {
-
 template<>
-struct data_type_traits<Color, void>
+struct matador::sql::data_type_traits<Color, void>
 {
     inline static data_type_t builtin_type(std::size_t size)
     { return data_type_traits<std::string>::builtin_type(size); }
@@ -62,13 +62,12 @@ struct data_type_traits<Color, void>
     {
         std::string enum_string;
         reader.read_value(id, index, enum_string, 64);
-    auto enum_opt = color_enum.to_enum(enum_string);
+        if (const auto enum_opt = color_enum.to_enum(enum_string)) {
-    if (enum_opt) {
             value = enum_opt.value();
         }
     }
 
-  static any_type create_value(Color &value)
+    static any_type create_value(const Color &value)
     {
         return color_enum.to_string(value);
     }
@@ -79,9 +78,6 @@ struct data_type_traits<Color, void>
     }
 };
 
-}
-
-
 TEST_CASE_METHOD(TypeTraitsTestFixture, "Special handling of attributes with type traits", "[typetraits]")
 {
   schema.attach<location>("location");
@@ -91,14 +87,14 @@ TEST_CASE_METHOD(TypeTraitsTestFixture, "Special handling of attributes with typ
     auto res = db
       .query(schema)
       .insert()
-      .into<location>("location")
+      .into("location", column_generator::generate<location>(schema, true))
       .values(loc)
       .execute();
     REQUIRE(res == 1);
 
     auto result = db
       .query(schema)
-      .select<location>()
+      .select(column_generator::generate<location>(schema, true))
       .from("location")
       .fetch_all<location>();
 
@@ -113,7 +109,7 @@ TEST_CASE_METHOD(TypeTraitsTestFixture, "Special handling of attributes with typ
     auto stmt = db
       .query(schema)
       .insert()
-      .into<location>("location")
+      .into("location", column_generator::generate<location>(schema, true))
       .values<location>()
       .prepare();
 
@@ -124,7 +120,7 @@ TEST_CASE_METHOD(TypeTraitsTestFixture, "Special handling of attributes with typ
 
     auto result = db
       .query(schema)
-      .select<location>()
+      .select(column_generator::generate<location>(schema, true))
       .from("location")
       .fetch_all<location>();
 

demo/author.json

@@ -0,0 +1,27 @@
+{
+  "name": "book",
+  "fields": {
+    "id": {
+      "type": "unsigned long",
+      "constraint": "primary_key"
+    },
+    "first_name": {
+      "type": "string",
+      "size": 63
+    },
+    "last_name": {
+      "type": "string",
+      "size": 63
+    },
+    "date_of_birth": {
+      "type": "string",
+      "size": 31
+    },
+    "year_of_birth": {
+      "type": "unsigned short"
+    },
+    "distinguished": {
+      "type": "boolean"
+    }
+  }
+}

demo/book.json

@@ -0,0 +1,23 @@
+{
+  "name": "book",
+  "fields": {
+    "id": {
+      "type": "unsigned long",
+      "constraint": "primary_key"
+    },
+    "title": {
+      "type": "string",
+      "size": 511
+    },
+    "book_author": {
+      "type": "author",
+      "constraint": {
+        "type": "foreign_key",
+        "references": "id"
+      }
+    },
+    "published_in": {
+      "type": "unsigned_short"
+    }
+  }
+}

demo/main.cpp

@@ -5,14 +5,14 @@
 #include "matador/sql/entity.hpp"
 
 #include "matador/utils/access.hpp"
+#include "matador/utils/enum_mapper.hpp"
 
 #include "matador/sql/query_helper.hpp"
 
 #include <iostream>
 #include <string>
 
-struct author
+struct author {
-{
     unsigned long id{};
     std::string first_name;
     std::string last_name;
@@ -21,8 +21,7 @@ struct author
     bool distinguished{false};
 
     template<typename Operator>
-  void process(Operator &op)
+    void process( Operator& op ) {
-  {
         namespace field = matador::utils::access;
         field::primary_key( op, "id", id );
         field::attribute( op, "first_name", first_name, 63 );
@@ -33,16 +32,14 @@ struct author
     }
 };
 
-struct book
+struct book {
-{
     unsigned long id{};
     matador::sql::entity<author> book_author;
     std::string title;
     unsigned short published_in{};
 
     template<typename Operator>
-  void process(Operator &op)
+    void process( Operator& op ) {
-  {
         namespace field = matador::utils::access;
         field::primary_key( op, "id", id );
         field::attribute( op, "title", title, 511 );
@@ -51,11 +48,125 @@ struct book
     }
 };
 
+struct payload {
+    unsigned long id{};
+
+    template<typename Operator>
+    void process( Operator& op ) {
+        namespace field = matador::utils::access;
+        field::primary_key( op, "id", id );
+    }
+};
+
+struct job {
+    enum class job_state {
+        Pending,
+        Running,
+        Succeeded,
+        Failed,
+        Canceled
+    };
+
+    enum class job_mode {
+        Foreground,
+        Background
+    };
+
+    unsigned long id{};
+    matador::sql::entity<payload> payload;
+    std::string type;
+    std::string description;
+    job_state state;
+    job_mode mode;
+
+    template<typename Operator>
+    void process( Operator& op ) {
+        namespace field = matador::utils::access;
+        field::primary_key( op, "id", id );
+        field::belongs_to( op, "payload", payload, matador::utils::default_foreign_attributes );
+        field::attribute( op, "type", type, 511 );
+        field::attribute( op, "description", description, 511 );
+        field::attribute( op, "state", state );
+        field::attribute( op, "mode", mode );
+    }
+};
+
+static const matador::utils::enum_mapper<job::job_state> job_state_enum({
+                                                           {job::job_state::Pending,  "Pending"},
+                                                           {job::job_state::Running,  "Running"},
+                                                           {job::job_state::Succeeded,  "Succeeded"},
+                                                           {job::job_state::Failed,  "Failed"},
+                                                           {job::job_state::Canceled,  "Canceled"}
+                                                           });
+
+static const matador::utils::enum_mapper<job::job_mode> job_mode_enum({
+                                                           {job::job_mode::Foreground,  "Foreground"},
+                                                           {job::job_mode::Background,  "Background"}
+                                                           });
+
+template<>
+struct matador::sql::data_type_traits<job::job_state, void>
+{
+    inline static data_type_t builtin_type(std::size_t size)
+    { return data_type_traits<std::string>::builtin_type(size); }
+
+    static void read_value(query_result_reader &reader, const char *id, size_t index, job::job_state &value)
+    {
+        std::string enum_string;
+        reader.read_value(id, index, enum_string, 64);
+        if (const auto enum_opt = job_state_enum.to_enum(enum_string)) {
+            value = enum_opt.value();
+        }
+    }
+
+    static any_type create_value(const job::job_state &value)
+    {
+        return job_state_enum.to_string(value);
+    }
+
+    static void bind_value(parameter_binder &binder, size_t index, job::job_state &value)
+    {
+        binder.bind(index, job_state_enum.to_string(value));
+    }
+};
+
+template<>
+struct matador::sql::data_type_traits<job::job_mode, void>
+{
+    inline static data_type_t builtin_type(std::size_t size)
+    { return data_type_traits<std::string>::builtin_type(size); }
+
+    static void read_value(query_result_reader &reader, const char *id, size_t index, job::job_mode &value)
+    {
+        std::string enum_string;
+        reader.read_value(id, index, enum_string, 64);
+        if (const auto enum_opt = job_mode_enum.to_enum(enum_string)) {
+            value = enum_opt.value();
+        }
+    }
+
+    static any_type create_value(const job::job_mode &value)
+    {
+        return job_mode_enum.to_string(value);
+    }
+
+    static void bind_value(parameter_binder &binder, size_t index, job::job_mode &value)
+    {
+        binder.bind(index, job_mode_enum.to_string(value));
+    }
+};
+
 QUERY_HELPER( authors, id, first_name, last_name, date_of_birth, year_of_birth, distinguished )
+
 QUERY_HELPER( books, id, author_id, title, published_in )
 
-int main()
+QUERY_HELPER( job, id, payload, type, description, state, mode )
-{
+
+QUERY_HELPER( payload, id )
+
+QUERY_HELPER( temporary_table, id );
+
+int main() {
     using namespace matador::sql;
     using namespace matador;
 
@@ -68,6 +179,7 @@ int main()
 
     connection c( dns );
     c.open();
+    s.create( c );
 
     auto create_authors_sql = c.query( s )
                                .create()
@@ -90,20 +202,18 @@ int main()
     mc.distinguished = true;
     auto insert_authors_sql = c.query( s )
                                .insert()
-    .into<author>(qh::authors)
+                               .into( qh::authors )
                                .values( mc )
                                .execute();
 
     std::cout << "SQL: " << insert_authors_sql << "\n";
 
     auto result = c.query( s )
-    .select<author>()
+                   .select( qh::authors.columns )
                    .from( qh::authors )
                    .fetch_all();
 
-  for (const auto &row: result) {
+    for (const auto& row: result) { std::cout << "Author " << row.at( qh::authors.first_name ) << "\n"; }
-    std::cout << "Author " << row.at(qh::authors.first_name) << "\n";
-  }
 
     auto update_authors_sql = c.query( s )
                                .update( qh::authors )
@@ -115,28 +225,26 @@ int main()
     std::cout << "SQL: " << update_authors_sql << "\n";
 
     auto authors = c.query( s )
-    .select<author>()
+                    .select( qh::authors.columns )
                     .from( qh::authors )
                     .fetch_all<author>();
 
-  for (const auto &a: authors) {
+    for (const auto& a: authors) { std::cout << "Author " << a.first_name << "\n"; }
-    std::cout << "Author " << a.first_name << "\n";
-  }
 
     c.query( s )
      .insert()
-    .into<book>(qh::books)
+     .into( qh::books )
      .values( {2, "It", mc.id, 1980} )
      .execute();
 
     c.query( s )
      .insert()
-    .into<book>(qh::books)
+     .into( qh::books )
      .values( {3, "Misery", mc.id, 1984} )
      .execute();
 
     auto select_books_sql = c.query( s )
-    .select<book>({qh::authors.last_name})
+                             .select( qh::books.columns, {qh::authors.last_name} )
                              .from( qh::books )
                              .join_left( qh::authors )
                              .on( qh::books.author_id == qh::authors.id )
@@ -147,9 +255,7 @@ int main()
                              .offset( 2 )
                              .fetch_all();
 
-  for (const auto &r: select_books_sql) {
+    for (const auto& r: select_books_sql) { std::cout << "R: " << r.at( qh::books.title ) << ", " << r.at( qh::authors.last_name ) << "\n"; }
-    std::cout << "R: " << r.at(qh::books.title) << ", " << r.at(qh::authors.last_name) << "\n";
-  }
     // SELECT book.title, book.id, book.author_id, book.published_in, author.name
     // FROM book
     // INNER JOIN author ON book.author_id = author.id
@@ -166,5 +272,24 @@ int main()
 
     std::cout << "SQL: " << drop_authors_sql << "\n";
 
+    auto res = c.query( s )
+                .select( {qh::payload.id} )
+                .from( qh::payload )
+                .join_left( qh::job )
+                .on( qh::job.payload == qh::payload.id )
+                .where(
+                        in( qh::payload.id, c.query( s )
+                                             .select( {qh::job.state} )
+                                             .from( qh::job )
+                                             .where( qh::job.state == job::job_state::Running )
+                                ) &&
+                        in( qh::payload.id, c.query( s )
+                                             .select( {qh::temporary_table.id} )
+                                             .from( qh::temporary_table ) )
+                        )
+                .build();
+    // .fetch_value<unsigned long>();
+    std::cout << "SQL: " << res.sql << "\n";
+
     return 0;
 }

include/matador/query/column.hpp

@@ -1,25 +0,0 @@
-#ifndef QUERY_COLUMN_HPP
-#define QUERY_COLUMN_HPP
-
-#include <string>
-
-namespace matador::query {
-
-class column {
-public:
-  column(const char *name); // NOLINT(*-explicit-constructor)
-  column(std::string name); // NOLINT(*-explicit-constructor)
-  column(std::string table_name, std::string name, std::string as);
-
-  column& as(std::string a);
-
-  std::string table;
-  std::string name;
-  std::string alias;
-};
-
-column operator "" _col(const char *name, size_t len);
-
-}
-
-#endif //QUERY_COLUMN_HPP

include/matador/query/query.hpp

@@ -1,22 +0,0 @@
-#ifndef QUERY_QUERY_HPP
-#define QUERY_QUERY_HPP
-
-#include "matador/query/query_parts.hpp"
-
-namespace matador::query {
-
-class connection;
-class query
-{
-public:
-  explicit query(connection &c);
-
-  query& select(const std::vector<column> &columns);
-  query& from(const std::string &table, const std::string &as = "");
-
-private:
-  connection &connection_;
-};
-
-}
-#endif //QUERY_QUERY_HPP

include/matador/query/query_builder.hpp

@@ -1,24 +0,0 @@
-#ifndef QUERY_QUERY_BUILDER_HPP
-#define QUERY_QUERY_BUILDER_HPP
-
-#include "matador/query/column.hpp"
-#include "matador/query/query_intermediates.hpp"
-
-#include "matador/sql/schema.hpp"
-
-#include <memory>
-
-namespace matador::query {
-
-class query_builder
-{
-public:
-  explicit query_builder(const std::shared_ptr<sql::schema> &scm);
-  query_select_intermediate select(std::initializer_list<column> columns);
-
-private:
-  std::shared_ptr<sql::schema> schema_;
-};
-
-}
-#endif //QUERY_QUERY_BUILDER_HPP

include/matador/query/query_compiler.hpp

@@ -1,37 +0,0 @@
-#ifndef QUERY_QUERY_COMPILER_HPP
-#define QUERY_QUERY_COMPILER_HPP
-
-#include "matador/query/query_part_visitor.hpp"
-#include "matador/query/query_parts.hpp"
-
-
-#include <typeindex>
-#include <string>
-
-namespace matador::sql {
-class dialect;
-}
-
-namespace matador::query {
-
-struct query_data;
-
-class query_compiler : public query_part_visitor
-{
-public:
-  explicit query_compiler(sql::dialect& d);
-
-  std::string compile(const query_data *data);
-
-private:
-  void visit(query_select_part &select_part) override;
-  void visit(query_from_part &from_part) override;
-
-private:
-  sql::dialect &dialect_;
-  std::string sql_;
-};
-
-}
-
-#endif //QUERY_QUERY_COMPILER_HPP

include/matador/query/query_data.hpp

@@ -1,24 +0,0 @@
-#ifndef QUERY_QUERY_DATA_HPP
-#define QUERY_QUERY_DATA_HPP
-
-#include "matador/query/query_parts.hpp"
-#include "matador/query/sql_commands.hpp"
-#include "matador/query/table.hpp"
-
-#include <memory>
-#include <vector>
-
-namespace matador::query {
-
-struct query_data
-{
-  SqlCommands command;
-  std::vector<std::unique_ptr<query_part>> parts;
-  std::vector<column> columns;
-  std::unordered_map<std::type_index, table_data> table_map_by_index;
-  using table_data_ref = std::reference_wrapper<table_data>;
-  std::unordered_map<std::string, table_data_ref> table_map_by_name;
-};
-
-}
-#endif //QUERY_QUERY_DATA_HPP

include/matador/query/query_intermediates.hpp

@@ -1,132 +0,0 @@
-#ifndef QUERY_QUERY_INTERMEDIATES_HPP
-#define QUERY_QUERY_INTERMEDIATES_HPP
-
-#include "matador/sql/schema.hpp"
-
-#include <string>
-#include <memory>
-
-namespace matador::sql {
-class basic_condition;
-}
-namespace matador::query {
-
-class query_from_intermediate;
-class query_join_intermediate;
-class query_on_intermediate;
-class query_where_intermediate;
-class query_group_by_intermediate;
-class query_order_by_intermediate;
-class query_order_direction_intermediate;
-class query_offset_intermediate;
-class query_limit_intermediate;
-
-class query_intermediate
-{
-public:
-  explicit query_intermediate(const std::shared_ptr<sql::schema> &scm);
-
-protected:
-  sql::schema& schema() const;
-
-private:
-  std::shared_ptr<sql::schema> schema_;
-};
-
-class query_select_finish_intermediate : public query_intermediate
-{
-public:
-  using query_intermediate::query_intermediate;
-
-  void compile();
-};
-
-class query_select_intermediate : public query_intermediate
-{
-public:
-  using query_intermediate::query_intermediate;
-
-  query_from_intermediate from(const std::string &table, const std::string &as = "");
-};
-
-class query_from_intermediate : public query_select_finish_intermediate
-{
-public:
-  using query_select_finish_intermediate::query_intermediate;
-
-  query_join_intermediate join(const std::string &join_table_name, const std::string &as);
-  query_where_intermediate where(const sql::basic_condition &cond);
-  query_group_by_intermediate group_by(const std::string &name);
-  query_order_by_intermediate order_by(const std::string &name);
-};
-
-class query_join_intermediate : public query_intermediate
-{
-public:
-  using query_intermediate::query_intermediate;
-
-  query_on_intermediate on(const std::string &column, const std::string &join_column);
-};
-
-class query_on_intermediate : public query_select_finish_intermediate
-{
-public:
-  using query_select_finish_intermediate::query_intermediate;
-
-  query_join_intermediate join(const std::string &join_table_name, const std::string &as);
-  query_where_intermediate where(const sql::basic_condition &cond);
-  query_group_by_intermediate group_by(const std::string &name);
-  query_order_by_intermediate order_by(const std::string &name);
-};
-
-class query_where_intermediate : public query_select_finish_intermediate
-{
-public:
-  using query_select_finish_intermediate::query_intermediate;
-
-  query_group_by_intermediate group_by(const std::string &name);
-  query_order_by_intermediate order_by(const std::string &name);
-};
-
-class query_group_by_intermediate : public query_select_finish_intermediate
-{
-public:
-  using query_select_finish_intermediate::query_intermediate;
-
-  query_order_by_intermediate order_by(const std::string &name);
-};
-
-class query_order_by_intermediate : public query_intermediate
-{
-public:
-  using query_intermediate::query_intermediate;
-
-  query_order_direction_intermediate asc();
-  query_order_direction_intermediate desc();
-};
-
-class query_order_direction_intermediate : public query_select_finish_intermediate
-{
-public:
-  using query_select_finish_intermediate::query_intermediate;
-
-  query_offset_intermediate offset(size_t offset);
-  query_limit_intermediate limit(size_t limit);
-};
-
-class query_offset_intermediate : public query_intermediate
-{
-public:
-  using query_intermediate::query_intermediate;
-
-  query_limit_intermediate limit(size_t limit);
-};
-
-class query_limit_intermediate : public query_select_finish_intermediate
-{
-public:
-  using query_select_finish_intermediate::query_intermediate;
-};
-
-}
-#endif //QUERY_QUERY_INTERMEDIATES_HPP

include/matador/query/query_part_visitor.hpp

@@ -1,19 +0,0 @@
-#ifndef QUERY_QUERY_PART_VISITOR_HPP
-#define QUERY_QUERY_PART_VISITOR_HPP
-
-namespace matador::query {
-
-class query_select_part;
-class query_from_part;
-
-class query_part_visitor
-{
-public:
-  virtual ~query_part_visitor() = default;
-
-  virtual void visit(query_select_part &select_part) = 0;
-  virtual void visit(query_from_part &from_part) = 0;
-};
-
-}
-#endif //QUERY_QUERY_PART_VISITOR_HPP

include/matador/query/query_parts.hpp

@@ -1,55 +0,0 @@
-#ifndef QUERY_QUERY_PARTS_HPP
-#define QUERY_QUERY_PARTS_HPP
-
-#include "matador/query/query_part_visitor.hpp"
-#include "matador/query/column.hpp"
-
-#include "matador/sql/dialect.hpp"
-
-namespace matador::query {
-
-class query_part
-{
-protected:
-  explicit query_part(sql::dialect::token_t token);
-
-public:
-  virtual ~query_part() = default;
-  virtual void accept(query_part_visitor &visitor) = 0;
-
-protected:
-  sql::dialect::token_t token_;
-};
-
-/**
- * Represents the SQL SELECT part
- */
-class query_select_part : public query_part
-{
-public:
-  explicit query_select_part(std::vector<column> columns);
-  void accept(query_part_visitor &visitor) override;
-
-private:
-  std::vector<column> columns_;
-};
-
-/**
- * Represents the SQL FROM part
- */
-class query_from_part : public query_part
-{
-public:
-  explicit query_from_part(std::string table_name);
-  query_from_part(std::string table_name, std::string as);
-
-private:
-  void accept(query_part_visitor &visitor) override;
-
-private:
-  std::string table_;
-  std::string alias_;
-};
-
-}
-#endif //QUERY_QUERY_PARTS_HPP

include/matador/query/sql_commands.hpp

@@ -1,31 +0,0 @@
-#ifndef QUERY_SQL_COMMANDS_HPP
-#define QUERY_SQL_COMMANDS_HPP
-
-#include "matador/utils/enum_mapper.hpp"
-
-namespace matador::query {
-
-enum class SqlCommands
-{
-  UNKNOWN,   /**< Unknown query command */
-  CREATE,    /**< Create query command */
-  DROP,      /**< Drop query command */
-  SELECT,    /**< Select query command */
-  INSERT,    /**< Insert query command */
-  UPDATE,    /**< Update query command */
-  REMOVE     /**< Remove query command */
-};
-
-static const utils::enum_mapper<SqlCommands> sql_command_enum({
-                                                                {SqlCommands::UNKNOWN, "unknown"},
-                                                                {SqlCommands::CREATE,  "create"},
-                                                                {SqlCommands::DROP,    "drop"},
-                                                                {SqlCommands::SELECT,  "select"},
-                                                                {SqlCommands::INSERT,  "insert"},
-                                                                {SqlCommands::UPDATE,  "update"},
-                                                                {SqlCommands::REMOVE,  "delete"}
-                                                              });
-
-}
-
-#endif //QUERY_SQL_COMMANDS_HPP

include/matador/query/table.hpp

@@ -1,16 +0,0 @@
-#ifndef QUERY_TABLE_HPP
-#define QUERY_TABLE_HPP
-
-#include <typeindex>
-#include <string>
-
-namespace matador::query {
-
-struct table_data
-{
-  std::type_index index;
-  std::string name;
-};
-
-}
-#endif //QUERY_TABLE_HPP

include/matador/sql/any_type.hpp

@@ -10,6 +10,17 @@
 
 namespace matador::sql {
 
+using any_db_type = std::variant<
+  long long,
+  unsigned long long,
+  double,
+  bool,
+  const char*,
+  std::string,
+  utils::blob,
+  placeholder,
+  nullptr_t>;
+
 using any_type = std::variant<
   char, short, int, long, long long,
   unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long,

include/matador/sql/basic_condition.hpp

@@ -33,7 +33,7 @@ public:
     LIKE
   };
 
-  virtual std::string evaluate(dialect &dialect, query_context &query) const = 0;
+  virtual std::string evaluate(const dialect &dialect, query_context &query) const = 0;
 
   static std::unordered_map<operand_t, std::string> operands;
 };

include/matador/sql/column.hpp

@@ -5,6 +5,8 @@
 
 namespace matador::sql {
 
+struct table;
+
 enum class sql_function_t {
   NONE,
   COUNT,
@@ -16,22 +18,18 @@ enum class sql_function_t {
 
 struct column
 {
-  column(const char *name) : name(name) {} // NOLINT(*-explicit-constructor)
+  column(const char *name); // NOLINT(*-explicit-constructor)
-  column(std::string name) : name(std::move(name)) {} // NOLINT(*-explicit-constructor)
+  column(std::string name); // NOLINT(*-explicit-constructor)
-  column(sql_function_t func, std::string name) : name(std::move(name)), function_(func) {} // NOLINT(*-explicit-constructor)
+  column(sql_function_t func, std::string name); // NOLINT(*-explicit-constructor)
-  column(std::string table_name, std::string name, std::string as)
+  column(std::string table_name, std::string name, std::string as = "");
-  : table(std::move(table_name))
+  column(std::string table_name, const char* name, std::string as = "");
-  , name(std::move(name))
+  column(struct table &t, const char* name, std::string as = "");
-  , alias(std::move(as)) {} // NOLINT(*-explicit-constructor)
 
-  column& as(std::string a) {
+  [[nodiscard]] bool equals(const column &x) const;
-    alias = std::move(a);
-    return *this;
-  }
 
-  [[nodiscard]] bool is_function() const {
+  column& as(std::string a);
-    return function_ != sql_function_t::NONE;
+
-  }
+  [[nodiscard]] bool is_function() const;
 
   std::string table;
   std::string name;

include/matador/sql/column_definition.hpp

@@ -46,13 +46,22 @@ public:
   column_definition(std::string name, data_type_t type, size_t index, std::string ref_table, std::string ref_column, utils::field_attributes attr, null_option null_opt);
 
   [[nodiscard]] const std::string& name() const;
-  [[nodiscard]] size_t index() const;
+  [[nodiscard]] int index() const;
   [[nodiscard]] const utils::field_attributes& attributes() const;
   [[nodiscard]] bool is_nullable() const;
   [[nodiscard]] data_type_t type() const;
   [[nodiscard]] const std::string& ref_table() const;
   [[nodiscard]] const std::string& ref_column() const;
 
+  [[nodiscard]] bool is_integer() const;
+  [[nodiscard]] bool is_floating_point() const;
+  [[nodiscard]] bool is_bool() const;
+  [[nodiscard]] bool is_string() const;
+  [[nodiscard]] bool is_varchar() const;
+  [[nodiscard]] bool is_blob() const;
+  [[nodiscard]] bool is_null() const;
+  [[nodiscard]] bool is_unknown() const;
+
   void type(data_type_t type);
 
   template< typename Type >
@@ -108,12 +117,10 @@ private:
   using data_type_index = std::vector<data_type_t>;
 
 private:
-  friend class record;
-
   static const data_type_index data_type_index_;
 
   std::string name_;
-  size_t index_{};
+  int index_{-1};
   utils::field_attributes attributes_;
   null_option null_option_{null_option::NOT_NULL};
   data_type_t type_{data_type_t::type_unknown};

include/matador/sql/column_definition_generator.hpp

@@ -0,0 +1,133 @@
+#ifndef QUERY_COLUMN_DEFINITION_GENERATOR_HPP
+#define QUERY_COLUMN_DEFINITION_GENERATOR_HPP
+
+#include "matador/sql/column_definition.hpp"
+#include "matador/sql/data_type_traits.hpp"
+
+#include "matador/utils/access.hpp"
+#include "matador/utils/field_attributes.hpp"
+#include "matador/utils/foreign_attributes.hpp"
+
+#include <typeindex>
+#include <vector>
+
+namespace matador::sql {
+
+class schema;
+
+class fk_column_generator
+{
+public:
+  fk_column_generator() = default;
+
+  template<class Type>
+  column_definition generate(const char *id, Type &x, const std::string &ref_table, const std::string &ref_column)
+  {
+    utils::access::process(*this, x);
+    return column_definition{id, type_, 0, ref_table, ref_column, {utils::constraints::FOREIGN_KEY }, null_option::NOT_NULL};
+  }
+
+  template<typename ValueType>
+  void on_primary_key(const char *, ValueType &/*pk*/, typename std::enable_if<std::is_integral<ValueType>::value && !std::is_same<bool, ValueType>::value>::type* = 0)
+  {
+    type_ = data_type_traits<ValueType>::builtin_type(0);
+  }
+  void on_primary_key(const char * /*id*/, std::string &/*pk*/, size_t size);
+  void on_revision(const char * /*id*/, unsigned long long &/*rev*/) {}
+  template < class Type >
+  void on_attribute(const char * /*id*/, Type &/*x*/, const utils::field_attributes &/*attr*/ = utils::null_attributes) {}
+  void on_attribute(const char * /*id*/, char * /*x*/, const utils::field_attributes &/*attr*/ = utils::null_attributes) {}
+  template<class Pointer>
+  void on_belongs_to(const char * /*id*/, Pointer &/*x*/, const utils::foreign_attributes &/*attr*/) {}
+  template<class Pointer>
+  void on_has_one(const char * /*id*/, Pointer &/*x*/, const utils::foreign_attributes &/*attr*/) {}
+  template<class ContainerType>
+  void on_has_many(ContainerType &, const char *, const utils::foreign_attributes &/*attr*/) {}
+  template<class ContainerType>
+  void on_has_many_to_many(const char *id, ContainerType &c, const char *join_column, const char *inverse_join_column, const utils::foreign_attributes &/*attr*/) {}
+  template<class ContainerType>
+  void on_has_many_to_many(const char *id, ContainerType &c, const utils::foreign_attributes &/*attr*/) {}
+
+private:
+  data_type_t type_{};
+};
+
+class column_definition_generator
+{
+private:
+  column_definition_generator(std::vector<column_definition> &columns, const schema &repo);
+
+public:
+  ~column_definition_generator() = default;
+
+  template < class Type >
+  static std::vector<column_definition> generate(const schema &repo)
+  {
+    std::vector<column_definition> columns;
+    column_definition_generator gen(columns, repo);
+    Type obj;
+    matador::utils::access::process(gen, obj);
+    return std::move(columns);
+  }
+
+  template < class V >
+  void on_primary_key(const char *, V &x, typename std::enable_if<std::is_integral<V>::value && !std::is_same<bool, V>::value>::type* = 0);
+  void on_primary_key(const char *id, std::string &pk, size_t size);
+  void on_revision(const char *id, unsigned long long &rev);
+
+  template<typename Type>
+  void on_attribute(const char *id, Type &x, const utils::field_attributes &attr = utils::null_attributes);
+
+  template<typename Type>
+  void on_attribute(const char *id, std::optional<Type> &x, const utils::field_attributes &attr = utils::null_attributes);
+
+  template<class Pointer>
+  void on_belongs_to(const char *id, Pointer &x, const utils::foreign_attributes &/*attr*/)
+  {
+    const auto [ref_table, ref_column] = determine_foreign_ref(std::type_index(typeid(typename Pointer::value_type)));
+    columns_.push_back(fk_column_generator_.generate(id, *x, ref_table, ref_column));
+  }
+  template<class Pointer>
+  void on_has_one(const char *id, Pointer &x, const utils::foreign_attributes &/*attr*/)
+  {
+    const auto [ref_table, ref_column] = determine_foreign_ref(std::type_index(typeid(typename Pointer::value_type)));
+    columns_.push_back(fk_column_generator_.generate(id, *x, ref_table, ref_column));
+  }
+  template<class ContainerType>
+  void on_has_many(ContainerType &, const char *, const utils::foreign_attributes &/*attr*/) {}
+  template<class ContainerType>
+  void on_has_many_to_many(const char *id, ContainerType &c, const char *join_column, const char *inverse_join_column, const utils::foreign_attributes &/*attr*/) {}
+  template<class ContainerType>
+  void on_has_many_to_many(const char *id, ContainerType &c, const utils::foreign_attributes &/*attr*/) {}
+
+private:
+  std::pair<std::string, std::string> determine_foreign_ref(const std::type_index &ti);
+
+private:
+  size_t index_ = 0;
+  std::vector<column_definition> &columns_;
+  const schema &repo_;
+
+  fk_column_generator fk_column_generator_;
+};
+
+template<typename V>
+void column_definition_generator::on_primary_key(const char *id, V &x, typename std::enable_if<std::is_integral<V>::value && !std::is_same<bool, V>::value>::type*)
+{
+  on_attribute(id, x, { utils::constraints::PRIMARY_KEY });
+}
+
+template<typename Type>
+void column_definition_generator::on_attribute(const char *id, Type &x, const utils::field_attributes &attr)
+{
+  columns_.emplace_back(id, x, attr, null_option::NOT_NULL);
+}
+
+template<typename Type>
+void column_definition_generator::on_attribute(const char *id, std::optional<Type> &x, const utils::field_attributes &attr)
+{
+  columns_.emplace_back(id, data_type_traits<Type>::builtin_type(attr.size()), attr, null_option::NULLABLE);
+}
+
+}
+#endif //QUERY_COLUMN_DEFINITION_GENERATOR_HPP

include/matador/sql/column_generator.hpp

@@ -1,129 +1,128 @@
 #ifndef QUERY_COLUMN_GENERATOR_HPP
 #define QUERY_COLUMN_GENERATOR_HPP
 
-#include "matador/sql/column_definition.hpp"
-#include "matador/sql/data_type_traits.hpp"
-
 #include "matador/utils/access.hpp"
 #include "matador/utils/field_attributes.hpp"
 #include "matador/utils/foreign_attributes.hpp"
 
-#include <typeindex>
+#include "matador/sql/column.hpp"
+#include "matador/sql/schema.hpp"
+
+#include <string>
 #include <vector>
+#include <stack>
 
 namespace matador::sql {
 
-class schema;
-
-class fk_column_generator
-{
-public:
-  fk_column_generator() = default;
-
-  template<class Type>
-  column_definition generate(const char *id, Type &x, const std::string &ref_table, const std::string &ref_column)
-  {
-    utils::access::process(*this, x);
-    return column_definition{id, type_, 0, ref_table, ref_column, {utils::constraints::FOREIGN_KEY }, null_option::NOT_NULL};
-  }
-
-  template<typename ValueType>
-  void on_primary_key(const char *, ValueType &/*pk*/, typename std::enable_if<std::is_integral<ValueType>::value && !std::is_same<bool, ValueType>::value>::type* = 0)
-  {
-    type_ = data_type_traits<ValueType>::builtin_type(0);
-  }
-  void on_primary_key(const char * /*id*/, std::string &/*pk*/, size_t size);
-  void on_revision(const char * /*id*/, unsigned long long &/*rev*/) {}
-  template < class Type >
-  void on_attribute(const char * /*id*/, Type &/*x*/, const utils::field_attributes &/*attr*/ = utils::null_attributes) {}
-  void on_attribute(const char * /*id*/, char * /*x*/, const utils::field_attributes &/*attr*/ = utils::null_attributes) {}
-  template<class Pointer>
-  void on_belongs_to(const char * /*id*/, Pointer &/*x*/, const utils::foreign_attributes &/*attr*/) {}
-  template<class Pointer>
-  void on_has_one(const char * /*id*/, Pointer &/*x*/, const utils::foreign_attributes &/*attr*/) {}
-  template<class ContainerType>
-  void on_has_many(const char *, ContainerType &, const char *, const char *, const utils::foreign_attributes &/*attr*/) {}
-  template<class ContainerType>
-  void on_has_many(const char *, ContainerType &, const utils::foreign_attributes &/*attr*/) {}
-
-private:
-  data_type_t type_{};
-};
-
 class column_generator
 {
 private:
-  column_generator(std::vector<column_definition> &columns, const schema &repo);
+  column_generator(std::vector<column> &column_infos,
+                   const sql::schema &ts,
+                   const std::string &table_name,
+                   bool force_lazy);
 
 public:
   ~column_generator() = default;
 
   template < class Type >
-  static std::vector<column_definition> generate(const schema &repo)
+  static std::vector<column> generate(const sql::schema &ts, bool force_lazy = false)
   {
-    std::vector<column_definition> columns;
+    const auto info = ts.info<Type>();
-    column_generator gen(columns, repo);
+    if (!info) {
+      return {};
+    }
+    std::vector<column> columns;
+    column_generator gen(columns, ts, info.value().name, force_lazy);
     Type obj;
     matador::utils::access::process(gen, obj);
     return std::move(columns);
   }
 
   template < class V >
-  void on_primary_key(const char *, V &x, typename std::enable_if<std::is_integral<V>::value && !std::is_same<bool, V>::value>::type* = 0);
+  void on_primary_key(const char *id, V &, typename std::enable_if<std::is_integral<V>::value && !std::is_same<bool, V>::value>::type* = 0)
-  void on_primary_key(const char *id, std::string &pk, size_t size);
+  {
-  void on_revision(const char *id, unsigned long long &rev);
+    push(id);
+  }
+  void on_primary_key(const char *id, std::string &, size_t);
+  void on_revision(const char *id, unsigned long long &/*rev*/);
 
   template<typename Type>
-  void on_attribute(const char *id, Type &x, const utils::field_attributes &attr = utils::null_attributes);
+  void on_attribute(const char *id, Type &, const utils::field_attributes &/*attr*/ = utils::null_attributes)
-
+  {
-  template<typename Type>
+    push(id);
-  void on_attribute(const char *id, std::optional<Type> &x, const utils::field_attributes &attr = utils::null_attributes);
+  }
 
   template<class Pointer>
-  void on_belongs_to(const char *id, Pointer &x, const utils::foreign_attributes &/*attr*/)
+  void on_belongs_to(const char *id, Pointer &, const utils::foreign_attributes &attr)
   {
-    const auto [ref_table, ref_column] = determine_foreign_ref(std::type_index(typeid(typename Pointer::value_type)));
+    if (attr.fetch() == utils::fetch_type::LAZY || force_lazy_) {
-    columns_.push_back(fk_column_generator_.generate(id, *x, ref_table, ref_column));
+      push(id);
+    } else {
+      const auto info = table_schema_.info<typename Pointer::value_type>();
+      if (!info) {
+        return;
+      }
+      table_name_stack_.push(info.value().name);
+      typename Pointer::value_type obj;
+      matador::utils::access::process(*this, obj);
+      table_name_stack_.pop();
+    }
   }
   template<class Pointer>
-  void on_has_one(const char *id, Pointer &x, const utils::foreign_attributes &/*attr*/)
+  void on_has_one(const char *id, Pointer &, const utils::foreign_attributes &attr)
   {
-    const auto [ref_table, ref_column] = determine_foreign_ref(std::type_index(typeid(typename Pointer::value_type)));
+    if (attr.fetch() == utils::fetch_type::LAZY || force_lazy_) {
-    columns_.push_back(fk_column_generator_.generate(id, *x, ref_table, ref_column));
+      push(id);
+    } else {
+      const auto info = table_schema_.info<typename Pointer::value_type>();
+      if (!info) {
+        return;
+      }
+      table_name_stack_.push(info.value().name);
+      typename Pointer::value_type obj;
+      matador::utils::access::process(*this, obj);
+      table_name_stack_.pop();
+    }
   }
   template<class ContainerType>
-  void on_has_many(const char *, ContainerType &, const char *, const char *, const utils::foreign_attributes &/*attr*/) {}
+  void on_has_many(ContainerType &, const char *, const utils::foreign_attributes &attr)
+  {
+    if (attr.fetch() == utils::fetch_type::LAZY || force_lazy_) {
+      return;
+    }
+    const auto info = table_schema_.info<typename ContainerType::value_type::value_type>();
+    if (!info) {
+      return;
+    }
+
+    table_name_stack_.push(info.value().name);
+    typename ContainerType::value_type::value_type obj;
+    matador::utils::access::process(*this, obj);
+    table_name_stack_.pop();
+  }
+
   template<class ContainerType>
-  void on_has_many(const char *, ContainerType &, const utils::foreign_attributes &/*attr*/) {}
+  void on_has_many_to_many(const char *id, ContainerType &c, const char *join_column, const char *inverse_join_column, const utils::foreign_attributes &attr)
+  {
+  }
+
+  template<class ContainerType>
+  void on_has_many_to_many(const char *id, ContainerType &c, const utils::foreign_attributes &attr)
+  {
+  }
 
 private:
-  std::pair<std::string, std::string> determine_foreign_ref(const std::type_index &ti);
+  void push(const std::string &column_name);
 
 private:
-  size_t index_ = 0;
+  std::stack<std::string> table_name_stack_;
-  std::vector<column_definition> &columns_;
+  std::vector<column> &column_infos_;
-  const schema &repo_;
+  const sql::schema &table_schema_;
-
+  int column_index{0};
-  fk_column_generator fk_column_generator_;
+  bool force_lazy_{false};
 };
 
-template<typename V>
-void column_generator::on_primary_key(const char *id, V &x, typename std::enable_if<std::is_integral<V>::value && !std::is_same<bool, V>::value>::type*)
-{
-  on_attribute(id, x, { utils::constraints::PRIMARY_KEY });
 }
 
-template<typename Type>
-void column_generator::on_attribute(const char *id, Type &x, const utils::field_attributes &attr)
-{
-  columns_.emplace_back(id, x, attr, null_option::NOT_NULL);
-}
-
-template<typename Type>
-void column_generator::on_attribute(const char *id, std::optional<Type> &x, const utils::field_attributes &attr)
-{
-  columns_.emplace_back(id, data_type_traits<Type>::builtin_type(attr.size()), attr, null_option::NULLABLE);
-}
-
-}
 #endif //QUERY_COLUMN_GENERATOR_HPP

include/matador/sql/column_name_generator.hpp

@@ -1,97 +0,0 @@
-#ifndef QUERY_COLUMN_NAME_GENERATOR_HPP
-#define QUERY_COLUMN_NAME_GENERATOR_HPP
-
-#include "matador/utils/access.hpp"
-#include "matador/utils/field_attributes.hpp"
-#include "matador/utils/foreign_attributes.hpp"
-
-#include "matador/sql/column.hpp"
-#include "matador/sql/schema.hpp"
-
-#include <string>
-#include <vector>
-#include <stack>
-
-namespace matador::sql {
-
-class column_name_generator
-{
-private:
-  column_name_generator(std::vector<column> &column_infos, const sql::schema &ts, const std::string &table_name);
-
-public:
-  ~column_name_generator() = default;
-
-  template < class Type >
-  static std::vector<column> generate(const sql::schema &ts)
-  {
-    const auto info = ts.info<Type>();
-    if (!info) {
-      return {};
-    }
-    std::vector<column> columns;
-    column_name_generator gen(columns, ts, info.value().name);
-    Type obj;
-    matador::utils::access::process(gen, obj);
-    return std::move(columns);
-  }
-
-  template < class V >
-  void on_primary_key(const char *id, V &, typename std::enable_if<std::is_integral<V>::value && !std::is_same<bool, V>::value>::type* = 0)
-  {
-    push(id);
-  }
-  void on_primary_key(const char *id, std::string &, size_t);
-  void on_revision(const char *id, unsigned long long &/*rev*/);
-
-  template<typename Type>
-  void on_attribute(const char *id, Type &, const utils::field_attributes &/*attr*/ = utils::null_attributes)
-  {
-    push(id);
-  }
-
-  template<class Pointer>
-  void on_belongs_to(const char *id, Pointer &, const utils::foreign_attributes &/*attr*/)
-  {
-    push(id);
-  }
-  template<class Pointer>
-  void on_has_one(const char *id, Pointer &, const utils::foreign_attributes &/*attr*/)
-  {
-    push(id);
-  }
-  template<class ContainerType>
-  void on_has_many(const char *, ContainerType &, const char *, const char *, const utils::foreign_attributes &attr)
-  {
-    if (attr.fetch() == utils::fetch_type::LAZY) {
-      return;
-    }
-    const auto info = table_schema_.info<typename ContainerType::value_type::value_type>();
-    if (!info) {
-      return;
-    }
-
-    table_name_stack_.push(info.value().name);
-    typename ContainerType::value_type::value_type obj;
-    matador::utils::access::process(*this, obj);
-    table_name_stack_.pop();
-  }
-  template<class ContainerType>
-  void on_has_many(const char *id, ContainerType &c, const utils::foreign_attributes &attr)
-  {
-    on_has_many(id, c, "", "", attr);
-  }
-
-private:
-  void push(const std::string &column_name);
-
-private:
-  std::stack<std::string> table_name_stack_;
-  std::vector<column> &column_infos_;
-  const sql::schema &table_schema_;
-  int column_index{0};
-};
-
-}
-
-#endif //QUERY_COLUMN_NAME_GENERATOR_HPP

include/matador/sql/condition.hpp

@@ -1,6 +1,8 @@
 #ifndef QUERY_CONDITION_HPP
 #define QUERY_CONDITION_HPP
 
+#include "matador/sql/any_type_to_string_visitor.hpp"
+#include "matador/sql/query_result.hpp"
 #include "matador/sql/basic_condition.hpp"
 #include "matador/sql/dialect.hpp"
 #include "matador/sql/placeholder.hpp"
@@ -26,6 +28,8 @@ namespace matador::sql {
 
 /// @cond MATADOR_DEV
 
+class query_select;
+
 template<class L, class R, class Enabled = void>
 class condition;
 
@@ -37,12 +41,13 @@ public:
 
     placeholder value;
 
-    std::string evaluate(dialect &d, query_context &query) const override;
+    std::string evaluate(const dialect &d, query_context &query) const override;
 };
 
 template<class T>
 class condition<column, T, typename std::enable_if<
   std::is_scalar<T>::value &&
+  !std::is_enum<T>::value &&
   !std::is_same<std::string, T>::value &&
   !std::is_same<const char*, T>::value>::type> : public basic_column_condition
 {
@@ -54,7 +59,7 @@ public:
 
   T value;
 
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     query.bind_vars.emplace_back(field_.name);
     return d.prepare_identifier(field_) + " " + operand + " " + std::to_string(value);
@@ -74,7 +79,7 @@ public:
 
   T value;
 
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     query.bind_vars.emplace_back(field_.name);
     return d.prepare_identifier(field_) + " " + operand + " '" + value + "'";
@@ -82,10 +87,32 @@ public:
 };
 
 template<class T>
-class condition<T, column, typename std::enable_if<
+class condition<column, T, std::enable_if_t<std::is_enum_v<T>>> final : public basic_column_condition
-  std::is_scalar<T>::value &&
+{
-  !std::is_same<std::string, T>::value &&
+public:
-  !std::is_same<const char*, T>::value>::type> : public basic_column_condition
+  condition(const column &fld, basic_condition::operand_t op, T val)
+    : basic_column_condition(fld, op)
+    , value(val)
+  { }
+
+  T value;
+
+  std::string evaluate(const dialect &d, query_context &query) const override
+  {
+    auto at = data_type_traits<T>::create_value(value);
+    any_type_to_string_visitor value_to_string(d, query);
+    std::visit(value_to_string, at);
+    return value_to_string.result + " " + operand + " " + d.prepare_identifier(field_);
+  }
+
+};
+
+
+template<class T>
+class condition<T, column, std::enable_if_t<
+  std::is_scalar_v<T> &&
+  !std::is_same_v<std::string, T> &&
+  !std::is_same_v<const char*, T>>> final : public basic_column_condition
 {
 public:
   condition(T val, basic_condition::operand_t op, const column &fld)
@@ -95,7 +122,7 @@ public:
 
   T value;
 
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     return std::to_string(value) + " " + operand + " " + d.prepare_identifier(field_);
   }
@@ -114,7 +141,7 @@ public:
 
   T value;
 
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     return "'" + std::to_string(value) + "' " + operand + " " + d.prepare_identifier(field_);
   }
@@ -156,7 +183,7 @@ public:
    * @param d The d used to evaluate
    * @return A condition IN part of the query
    */
-  std::string evaluate(dialect &d, query_context &query) const override {
+  std::string evaluate(const dialect &d, query_context &query) const override {
     auto count = size();
     for (size_t i = 0; i < count; ++i) {
       query.bind_vars.emplace_back(field_.name);
@@ -215,7 +242,7 @@ public:
    * @param op Operand of the condition
    * @param q The query to be evaluated to the IN arguments
    */
-  condition(column col, basic_condition::operand_t op, query_context &q);
+  condition(column col, basic_condition::operand_t op, const query_context &q);
 
   /**
    * @brief Evaluates the condition
@@ -226,10 +253,10 @@ public:
    * @param d The d used to evaluate
    * @return A condition IN part of the query
    */
-  std::string evaluate(dialect &d, query_context &query) const override;
+  std::string evaluate(const dialect &d, query_context &query) const override;
 
 private:
-  query_context &query_;
+  query_context query_;
 };
 
 /**
@@ -261,7 +288,7 @@ public:
    * @param d The d used to evaluate
    * @return A condition BETWEEN part of the query
    */
-  std::string evaluate(dialect &d, query_context &query) const override {
+  std::string evaluate(const dialect &d, query_context &query) const override {
     query.bind_vars.emplace_back(field_.name);
     query.bind_vars.emplace_back(field_.name);
     return d.prepare_identifier(field_) + " BETWEEN " + std::to_string(range_.first) + " AND " + std::to_string(range_.second);
@@ -303,7 +330,7 @@ public:
    * @param d The d used to evaluate
    * @return The evaluated string based on the compile type
    */
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     // ensure the numbering order for host vars
     auto cl = left.evaluate(d, query);
@@ -346,7 +373,7 @@ public:
    * @param d The d used to evaluate
    * @return The evaluated string based on the compile type
    */
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     return operand + " (" + cond.evaluate(d) + ")";
   }
@@ -369,7 +396,7 @@ public:
    * @param d The d used to evaluate
    * @return The evaluated string based on the compile type
    */
-  std::string evaluate(dialect &d, query_context &query) const override
+  std::string evaluate(const dialect &d, query_context &query) const override
   {
     return d.prepare_identifier(field_) + " " + operand + " " + d.prepare_identifier(other_column_);
   }
@@ -415,7 +442,8 @@ condition<column, std::initializer_list<V>> in(const column &col, std::initializ
  * @param q The query to be executes as sub select
  * @return The condition object
  */
-condition<column, query_context> in(const column &col, query_context &&q);
+condition<column, query_context> in(const column &col, const query_context &q);
+condition<column, query_context> in(const column &col, const query_select &q);
 
 /**
  * @brief Creates a between condition.

include/matador/sql/connection.hpp

@@ -9,7 +9,6 @@
 #include "matador/sql/query_result.hpp"
 #include "matador/sql/record.hpp"
 #include "matador/sql/statement.hpp"
-#include "matador/sql/schema.hpp"
 
 #include "matador/utils/logger.hpp"
 
@@ -17,6 +16,8 @@
 
 namespace matador::sql {
 
+class schema;
+
 class connection
 {
 public:
@@ -32,7 +33,7 @@ public:
   [[nodiscard]] bool is_open() const;
   [[nodiscard]] const connection_info& info() const;
 
-  [[nodiscard]] record describe(const std::string &table_name) const;
+  [[nodiscard]] std::vector<sql::column_definition> describe(const std::string &table_name) const;
   [[nodiscard]] bool exists(const std::string &schema_name, const std::string &table_name) const;
   [[nodiscard]] bool exists(const std::string &table_name) const;
 

include/matador/sql/connection_impl.hpp

@@ -26,7 +26,7 @@ public:
   virtual std::unique_ptr<query_result_impl> fetch(const std::string &stmt) = 0;
   virtual std::unique_ptr<statement_impl> prepare(query_context context) = 0;
 
-  virtual record describe(const std::string &table) = 0;
+  virtual std::vector<sql::column_definition> describe(const std::string &table) = 0;
   virtual bool exists(const std::string &schema_name, const std::string &table_name) = 0;
 
 protected:

include/matador/sql/connection_pool.hpp

@@ -7,6 +7,7 @@
 #include <mutex>
 #include <string>
 #include <optional>
+#include <condition_variable>
 #include <thread>
 #include <unordered_map>
 
@@ -86,19 +87,21 @@ public:
   }
 
   connection_pointer acquire() {
+    std::unique_lock<std::mutex> lock(mutex_);
+    while (idle_connections_.empty()) {
+      cv.wait(lock);
+    }
+
+    return get_next_connection();
+  }
+
+  connection_pointer try_acquire() {
     std::unique_lock<std::mutex> lock(mutex_);
     if (idle_connections_.empty()) {
       return {nullptr, this};
     }
 
-    pointer next_connection{nullptr};
+    return get_next_connection();
-    for (auto &item : idle_connections_) {
-      next_connection = item.second;
-      auto node = idle_connections_.extract(item.first);
-      inuse_connections_.insert(std::move(node));
-      break;
-    }
-    return {next_connection, this};
   }
 
   connection_pointer acquire(size_t id) {
@@ -151,8 +154,21 @@ public:
   const connection_info &info() const {
     return info_;
   }
+
+private:
+  connection_pointer get_next_connection() {
+    pointer next_connection{nullptr};
+    for (auto &item : idle_connections_) {
+      next_connection = item.second;
+      auto node = idle_connections_.extract(item.first);
+      inuse_connections_.insert(std::move(node));
+      break;
+    }
+    return {next_connection, this};
+  }
 private:
   mutable std::mutex mutex_;
+  std::condition_variable cv;
   std::vector<IdConnection<Connection>> connection_repo_;
   using pointer = IdConnection<Connection>*;
   using connection_map = std::unordered_map<size_t, pointer>;

include/matador/sql/convert.hpp

@@ -55,6 +55,12 @@ void convert(std::string &dest, SourceType source, typename std::enable_if<std::
   }
 }
 
+template < typename SourceType >
+void convert(utils::blob &dest, SourceType source, typename std::enable_if<!std::is_same<utils::blob, SourceType>::value>::type* = nullptr)
+{
+  throw std::logic_error("couldn't convert value to matador::utils::blob");
+}
+
 void convert(std::string &dest, const char* source);
 
 unsigned long long to_unsigned_long_long(const char *source);
@@ -108,8 +114,11 @@ void convert(DestType &dest, bool source, typename std::enable_if<std::is_floati
 template < typename DestType >
 void convert(DestType &dest, const utils::blob &data)
 {
+  throw std::logic_error("couldn't convert matador::utils::blob into destination type");
 }
 
+void convert(utils::blob &dest, const utils::blob &data);
+
 }
 
 #endif //QUERY_CONVERT_HPP

include/matador/sql/data_type_traits.hpp

@@ -53,13 +53,22 @@ template < class Type, class Enable = void >
 struct data_type_traits;
 
 /// @cond MATADOR_DEV
+template <> struct data_type_traits<nullptr_t, void>
+{
+  inline static data_type_t builtin_type(std::size_t /*size*/) { return data_type_t::type_null; }
+  static void read_value(query_result_reader &reader, const char *id, size_t index, nullptr_t &/*value*/);
+  static void bind_value(parameter_binder &binder, size_t index, nullptr_t &/*value*/);
+  static void bind_result_value(result_parameter_binder &binder, size_t index, nullptr_t &/*value*/);
+  inline static any_type create_value(const char &value) { return value; }
+};
+
 template <> struct data_type_traits<char, void>
 {
   inline static data_type_t builtin_type(std::size_t /*size*/) { return data_type_t::type_char; }
   static void read_value(query_result_reader &reader, const char *id, size_t index, char &value);
   static void bind_value(parameter_binder &binder, size_t index, char &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, char &value);
-  inline static any_type create_value(char &value) { return value; }
+  inline static any_type create_value(const char &value) { return value; }
 };
 
 template <> struct data_type_traits<short, void>
@@ -68,7 +77,7 @@ template <> struct data_type_traits<short, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, short &value);
   static void bind_value(parameter_binder &binder, size_t index, short &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, short &value);
-  inline static any_type create_value(short &value) { return value; }
+  inline static any_type create_value(const short &value) { return value; }
 };
 
 template <> struct data_type_traits<int, void>
@@ -77,7 +86,7 @@ template <> struct data_type_traits<int, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, int &value);
   static void bind_value(parameter_binder &binder, size_t index, int &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, int &value);
-  inline static any_type create_value(int &value) { return value; }
+  inline static any_type create_value(const int &value) { return value; }
 };
 
 template <> struct data_type_traits<long, void>
@@ -86,7 +95,7 @@ template <> struct data_type_traits<long, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, long &value);
   static void bind_value(parameter_binder &binder, size_t index, long &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, long &value);
-  inline static any_type create_value(long &value) { return value; }
+  inline static any_type create_value(const long &value) { return value; }
 };
 
 template <> struct data_type_traits<long long, void>
@@ -95,7 +104,7 @@ template <> struct data_type_traits<long long, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, long long &value);
   static void bind_value(parameter_binder &binder, size_t index, long long &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, long long &value);
-  inline static any_type create_value(long long &value) { return value; }
+  inline static any_type create_value(const long long &value) { return value; }
 };
 
 template <> struct data_type_traits<unsigned char, void>
@@ -104,7 +113,7 @@ template <> struct data_type_traits<unsigned char, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, unsigned char &value);
   static void bind_value(parameter_binder &binder, size_t index, unsigned char &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, unsigned char &value);
-  inline static any_type create_value(unsigned char &value) { return value; }
+  inline static any_type create_value(const unsigned char &value) { return value; }
 };
 
 template <> struct data_type_traits<unsigned short, void>
@@ -113,7 +122,7 @@ template <> struct data_type_traits<unsigned short, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, unsigned short &value);
   static void bind_value(parameter_binder &binder, size_t index, unsigned short &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, unsigned short &value);
-  inline static any_type create_value(unsigned short &value) { return value; }
+  inline static any_type create_value(const unsigned short &value) { return value; }
 };
 
 template <> struct data_type_traits<unsigned int, void>
@@ -122,7 +131,7 @@ template <> struct data_type_traits<unsigned int, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, unsigned int &value);
   static void bind_value(parameter_binder &binder, size_t index, unsigned int &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, unsigned int &value);
-  inline static any_type create_value(unsigned int &value) { return value; }
+  inline static any_type create_value(const unsigned int &value) { return value; }
 };
 
 template <> struct data_type_traits<unsigned long, void>
@@ -131,7 +140,7 @@ template <> struct data_type_traits<unsigned long, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, unsigned long &value);
   static void bind_value(parameter_binder &binder, size_t index, unsigned long &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, unsigned long &value);
-  inline static any_type create_value(unsigned long &value) { return value; }
+  inline static any_type create_value(const unsigned long &value) { return value; }
 };
 
 template <> struct data_type_traits<unsigned long long, void>
@@ -140,7 +149,7 @@ template <> struct data_type_traits<unsigned long long, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, unsigned long long &value);
   static void bind_value(parameter_binder &binder, size_t index, unsigned long long &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, unsigned long long &value);
-  inline static any_type create_value(unsigned long long &value) { return value; }
+  inline static any_type create_value(const unsigned long long &value) { return value; }
 };
 
 template <> struct data_type_traits<bool, void>
@@ -149,7 +158,7 @@ template <> struct data_type_traits<bool, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, bool &value);
   static void bind_value(parameter_binder &binder, size_t index, bool &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, bool &value);
-  inline static any_type create_value(bool &value) { return value; }
+  inline static any_type create_value(const bool &value) { return value; }
 };
 
 template <> struct data_type_traits<float, void>
@@ -158,7 +167,7 @@ template <> struct data_type_traits<float, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, float &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, float &value);
   static void bind_value(parameter_binder &binder, size_t index, float &value);
-  inline static any_type create_value(float &value) { return value; }
+  inline static any_type create_value(const float &value) { return value; }
 };
 
 template <> struct data_type_traits<double, void>
@@ -167,7 +176,7 @@ template <> struct data_type_traits<double, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, double &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, double &value);
   static void bind_value(parameter_binder &binder, size_t index, double &value);
-  inline static any_type create_value(double &value) { return value; }
+  inline static any_type create_value(const double &value) { return value; }
 };
 
 template <> struct data_type_traits<const char*, void>
@@ -194,16 +203,16 @@ template <> struct data_type_traits<std::string, void>
   static void read_value(query_result_reader &reader, const char *id, size_t index, std::string &value, size_t size);
   static void bind_value(parameter_binder &binder, size_t index, std::string &value, size_t size = 0);
   static void bind_result_value(result_parameter_binder &binder, size_t index, std::string &value, size_t size = 0);
-  inline static any_type create_value(std::string &value) { return value; }
+  inline static any_type create_value(const std::string &value) { return value; }
 };
 
 template <> struct data_type_traits<utils::blob, void>
 {
-  inline static data_type_t builtin_type(std::size_t size) { return data_type_t::type_blob; }
+  inline static data_type_t builtin_type(std::size_t /*size*/) { return data_type_t::type_blob; }
   static void read_value(query_result_reader &reader, const char *id, size_t index, utils::blob &value);
   static void bind_value(parameter_binder &binder, size_t index, utils::blob &value);
   static void bind_result_value(result_parameter_binder &binder, size_t index, utils::blob &value);
-  inline static any_type create_value(utils::blob &value) { return value; }
+  inline static any_type create_value(const utils::blob &value) { return value; }
 };
 
 //template <> struct data_type_traits<matador::date>
@@ -223,7 +232,7 @@ template <> struct data_type_traits<utils::blob, void>
 //};
 
 template < typename EnumType >
-struct data_type_traits<EnumType, typename std::enable_if<std::is_enum<EnumType>::value>::type>
+struct data_type_traits<EnumType, std::enable_if_t<std::is_enum_v<EnumType>>>
 {
   inline static data_type_t builtin_type(std::size_t /*size*/) { return data_type_t::type_int; }
   static void read_value(query_result_reader &reader, const char *id, size_t index, EnumType &value)
@@ -232,13 +241,15 @@ struct data_type_traits<EnumType, typename std::enable_if<std::is_enum<EnumType>
   }
   static void bind_value(parameter_binder &binder, size_t index, EnumType &value)
   {
-    data_type_traits<int>::bind_value(binder, index, (int&)value);
+    data_type_traits<int>::bind_value(binder, index, static_cast<int&>(value));
   }
   static void bind_result_value(result_parameter_binder &binder, size_t index, EnumType &value)
   {
-    data_type_traits<int>::bind_result_value(binder, index, (int&)value);
+    data_type_traits<int>::bind_result_value(binder, index, static_cast<int&>(value));
+  }
+  static any_type create_value(const EnumType &value) {
+      return static_cast<int>(value);
   }
-  inline static any_type create_value(EnumType &value) { return (int)value; }
 };
 /// @endcond
 

include/matador/sql/entity.hpp

@@ -33,6 +33,8 @@ public:
   pointer get() { return obj_.get(); }
   const value_type* get() const { return obj_.get(); }
 
+  operator bool() const { return obj_.get() != nullptr; } // NOLINT(*-explicit-constructor)
+
 private:
   std::shared_ptr<value_type> obj_;
 };

include/matador/sql/entity_query_builder.hpp

@@ -0,0 +1,283 @@
+#ifndef QUERY_ENTITY_QUERY_BUILDER_HPP
+#define QUERY_ENTITY_QUERY_BUILDER_HPP
+
+#include "matador/sql/connection.hpp"
+#include "matador/sql/condition.hpp"
+#include "matador/sql/query_context.hpp"
+#include "matador/sql/query.hpp"
+#include "matador/sql/query_intermediates.hpp"
+#include "matador/sql/value.hpp"
+
+#include "matador/utils/result.hpp"
+
+#include <iostream>
+
+namespace matador::sql {
+
+struct join_columns
+{
+  std::string join_column;
+  std::string inverse_join_column;
+};
+
+class join_column_collector
+{
+public:
+  template<class Type>
+  join_columns collect()
+  {
+    join_columns_ = {};
+    Type obj;
+
+    matador::utils::access::process(*this, obj);
+
+    return join_columns_;
+  }
+  template < class V >
+  void on_primary_key(const char * /*id*/, V &, typename std::enable_if<std::is_integral<V>::value && !std::is_same<bool, V>::value>::type* = 0) {}
+  void on_primary_key(const char * /*id*/, std::string &, size_t) {}
+  void on_revision(const char * /*id*/, unsigned long long &/*rev*/) {}
+  template<typename Type>
+  void on_attribute(const char * /*id*/, Type &, const utils::field_attributes &/*attr*/ = utils::null_attributes) {}
+  template<class Pointer>
+  void on_belongs_to(const char * /*id*/, Pointer &obj, const utils::foreign_attributes &attr) {}
+  template<class Pointer>
+  void on_has_one(const char * /*id*/, Pointer &obj, const utils::foreign_attributes &attr) {}
+  template<class ContainerType>
+  void on_has_many(ContainerType &, const char *join_column, const utils::foreign_attributes &attr) {}
+  template<class ContainerType>
+  void on_has_many_to_many(const char * /*id*/, ContainerType &/*c*/, const char *join_column, const char *inverse_join_column, const utils::foreign_attributes &/*attr*/)
+  {
+    join_columns_.join_column = join_column;
+    join_columns_.inverse_join_column = inverse_join_column;
+  }
+  template<class ContainerType>
+  void on_has_many_to_many(const char * /*id*/, ContainerType &/*c*/, const utils::foreign_attributes &/*attr*/) {}
+
+private:
+  join_columns join_columns_;
+};
+
+struct entity_query_data {
+  std::string root_table_name;
+  std::string pk_column_;
+  std::vector<column> columns;
+  std::vector<join_data> joins;
+  std::unique_ptr<basic_condition> where_clause;
+};
+
+enum class query_build_error : std::uint8_t {
+  Ok = 0,
+  UnknownType,
+  MissingPrimaryKey,
+  UnexpectedError
+};
+
+class query_builder_exception : public std::exception
+{
+public:
+  explicit query_builder_exception(query_build_error error) : error_(error) {}
+
+  [[nodiscard]] query_build_error error() const { return error_; }
+
+private:
+  const query_build_error error_;
+};
+
+class entity_query_builder
+{
+public:
+  explicit entity_query_builder(const schema &scm)
+  : schema_(scm) {}
+
+  template<class EntityType, typename PrimaryKeyType>
+  utils::result<entity_query_data, query_build_error> build(const PrimaryKeyType &pk) {
+    const auto info = schema_.info<EntityType>();
+    if (!info) {
+      return utils::error(query_build_error::UnknownType);
+    }
+    pk_ = pk;
+    table_info_stack_.push(info.value());
+    entity_query_data_ = { info->name };
+    EntityType obj;
+    try {
+      matador::utils::access::process(*this, obj);
+
+      return {utils::ok(std::move(entity_query_data_))};
+    } catch (const query_builder_exception &ex) {
+      return {utils::error(ex.error())};
+    } catch (...) {
+      return {utils::error(query_build_error::UnexpectedError)};
+    }
+  }
+
+  template<class EntityType>
+  utils::result<entity_query_data, query_build_error> build() {
+    const auto info = schema_.info<EntityType>();
+    if (!info) {
+      return utils::error(query_build_error::UnknownType);
+    }
+    pk_ = nullptr;
+    table_info_stack_.push(info.value());
+    entity_query_data_ = { info->name };
+    EntityType obj;
+    try {
+      matador::utils::access::process(*this, obj);
+
+      return {utils::ok(std::move(entity_query_data_))};
+    } catch (const query_builder_exception &ex) {
+      return {utils::error(ex.error())};
+    } catch (...) {
+      return {utils::error(query_build_error::UnexpectedError)};
+    }
+  }
+
+  template < class V >
+  void on_primary_key(const char *id, V &, typename std::enable_if<std::is_integral<V>::value && !std::is_same<bool, V>::value>::type* = 0)
+  {
+    push(id);
+    if (!is_root_entity()) {
+      return;
+    }
+    if (pk_.is_null()) {
+      entity_query_data_.pk_column_ = id;
+    } else if (pk_.is_integer()) {
+      entity_query_data_.where_clause = make_condition(column{table_info_stack_.top().name, id, ""} == *pk_.as<V>());
+      entity_query_data_.pk_column_ = id;
+    }
+  }
+
+  void on_primary_key(const char *id, std::string &, size_t);
+  void on_revision(const char *id, unsigned long long &/*rev*/);
+
+  template<typename Type>
+  void on_attribute(const char *id, Type &, const utils::field_attributes &/*attr*/ = utils::null_attributes)
+  {
+    push(id);
+  }
+
+  template<class Pointer>
+  void on_belongs_to(const char *id, Pointer &obj, const utils::foreign_attributes &attr)
+  {
+    on_foreign_object(id, obj, attr);
+  }
+
+  template<class Pointer>
+  void on_has_one(const char *id, Pointer &obj, const utils::foreign_attributes &attr)
+  {
+    on_foreign_object(id, obj, attr);
+  }
+
+  template<class ContainerType>
+  void on_has_many(ContainerType &, const char *join_column, const utils::foreign_attributes &attr)
+  {
+    if (attr.fetch() == utils::fetch_type::EAGER) {
+      const auto info = schema_.info<typename ContainerType::value_type::value_type>();
+      if (!info) {
+        throw query_builder_exception{query_build_error::UnknownType};
+      }
+      table_info_stack_.push(info.value());
+      typename ContainerType::value_type::value_type obj;
+      matador::utils::access::process(*this , obj);
+      table_info_stack_.pop();
+
+      auto pk = info->prototype.primary_key();
+      if (!pk) {
+        throw query_builder_exception{query_build_error::MissingPrimaryKey};
+      }
+
+      append_join({table_info_stack_.top().name, table_info_stack_.top().prototype.primary_key()->name()}, {info->name, join_column});
+    }
+  }
+
+  template<class ContainerType>
+  void on_has_many_to_many(const char *id, ContainerType &c, const char *join_column, const char *inverse_join_column, const utils::foreign_attributes &attr)
+  {
+    if (attr.fetch() != utils::fetch_type::EAGER) {
+      return;
+    }
+    const auto info = schema_.info<typename ContainerType::value_type::value_type>();
+    if (!info) {
+      throw query_builder_exception{query_build_error::UnknownType};
+    }
+    table_info_stack_.push(info.value());
+    typename ContainerType::value_type::value_type obj;
+    matador::utils::access::process(*this , obj);
+    table_info_stack_.pop();
+
+    auto pk = info->prototype.primary_key();
+    if (!pk) {
+      throw query_builder_exception{query_build_error::MissingPrimaryKey};
+    }
+
+    append_join({table_info_stack_.top().name, table_info_stack_.top().prototype.primary_key()->name()}, {id, join_column});
+    append_join({id, inverse_join_column}, {info->name, pk->name()});
+  }
+
+  template<class ContainerType>
+  void on_has_many_to_many(const char *id, ContainerType &c, const utils::foreign_attributes &attr)
+  {
+    if (attr.fetch() != utils::fetch_type::EAGER) {
+      return;
+    }
+    const auto info = schema_.info<typename ContainerType::value_type::value_type>();
+    if (!info) {
+      throw query_builder_exception{query_build_error::UnknownType};
+    }
+    table_info_stack_.push(info.value());
+    typename ContainerType::value_type::value_type obj;
+    matador::utils::access::process(*this , obj);
+    table_info_stack_.pop();
+
+    auto pk = info->prototype.primary_key();
+    if (!pk) {
+      throw query_builder_exception{query_build_error::MissingPrimaryKey};
+    }
+
+    const auto join_columns = join_column_collector_.collect<typename ContainerType::value_type::value_type>();
+
+    append_join({table_info_stack_.top().name, table_info_stack_.top().prototype.primary_key()->name()}, {id, join_columns.inverse_join_column});
+    append_join({id, join_columns.join_column}, {info->name, pk->name()});
+  }
+
+private:
+  template<class Pointer>
+  void on_foreign_object(const char *id, Pointer &, const utils::foreign_attributes &attr);
+  void push(const std::string &column_name);
+  [[nodiscard]] bool is_root_entity() const;
+  void append_join(const column &left, const column &right);
+
+private:
+  value pk_;
+  std::stack<table_info> table_info_stack_;
+  const schema &schema_;
+  entity_query_data entity_query_data_;
+  int column_index{0};
+  join_column_collector join_column_collector_;
+};
+
+template<class Pointer>
+void entity_query_builder::on_foreign_object(const char *id, Pointer &, const utils::foreign_attributes &attr)
+{
+  if (attr.fetch() == utils::fetch_type::EAGER) {
+    const auto info = schema_.info<typename Pointer::value_type>();
+    if (!info) {
+      throw query_builder_exception{query_build_error::UnknownType};
+    }
+    table_info_stack_.push(info.value());
+    typename Pointer::value_type obj;
+    matador::utils::access::process(*this, obj);
+    table_info_stack_.pop();
+
+    auto pk = info->prototype.primary_key();
+    if (!pk) {
+      throw query_builder_exception{query_build_error::MissingPrimaryKey};
+    }
+    append_join({table_info_stack_.top().name, id}, {info->name, pk->name()});
+  } else {
+    push(id);
+  }
+}
+
+}
+#endif //QUERY_ENTITY_QUERY_BUILDER_HPP

include/matador/sql/field.hpp

@@ -0,0 +1,73 @@
+#ifndef QUERY_FIELD_HPP
+#define QUERY_FIELD_HPP
+
+#include "matador/sql/value.hpp"
+
+#include <optional>
+#include <string>
+
+namespace matador::sql {
+
+class field
+{
+public:
+  explicit field(std::string name);
+  template<typename Type>
+  field(std::string name, Type value, size_t size = 0, int index = -1)
+  : name_(std::move(name))
+  , index_(index)
+  , value_(value, size) {}
+  field(std::string name, data_type_t data_type, size_t size = 0, int index = -1);
+  field(const field &x) = default;
+  field& operator=(const field &x) = default;
+  field(field &&x) noexcept;
+  field& operator=(field &&x) noexcept;
+
+  template<typename Type>
+  field& operator=(Type value) {
+    value_ = std::move(value);
+
+    return *this;
+  }
+
+  [[nodiscard]] const std::string& name() const;
+  [[nodiscard]] size_t size() const;
+  [[nodiscard]] int index() const;
+
+  template<class Type>
+  std::optional<Type> as() const
+  {
+    return value_.as<Type>();
+  }
+
+  [[nodiscard]] std::string str() const;
+
+  [[nodiscard]] bool is_integer() const;
+  [[nodiscard]] bool is_floating_point() const;
+  [[nodiscard]] bool is_bool() const;
+  [[nodiscard]] bool is_string() const;
+  [[nodiscard]] bool is_varchar() const;
+  [[nodiscard]] bool is_blob() const;
+  [[nodiscard]] bool is_null() const;
+  [[nodiscard]] bool is_unknown() const;
+
+  friend std::ostream& operator<<(std::ostream &out, const field &col);
+
+private:
+  template<class Operator>
+  void process(Operator &op)
+  {
+    op.on_attribute(name_.c_str(), value_, value_.size());
+  }
+
+private:
+  friend class record;
+
+  std::string name_;
+  int index_{-1};
+
+  value value_;
+};
+
+}
+#endif //QUERY_FIELD_HPP

include/matador/sql/has_many_to_many_relation.hpp

@@ -0,0 +1,38 @@
+#ifndef QUERY_HAS_MANY_TO_MANY_RELATION_HPP
+#define QUERY_HAS_MANY_TO_MANY_RELATION_HPP
+
+#include "matador/sql/entity.hpp"
+
+#include "matador/utils/access.hpp"
+#include "matador/utils/foreign_attributes.hpp"
+
+namespace matador::sql {
+
+template < class LocalType, class ForeignType >
+class has_many_to_many_relation
+{
+public:
+  has_many_to_many_relation() = default;
+  has_many_to_many_relation(std::string local_name, std::string remote_name)
+  : local_name_(std::move(local_name))
+  , remote_name_(std::move(remote_name)) {}
+
+  template<class Operator>
+  void process(Operator &op) {
+    namespace field = matador::utils::access;
+    field::belongs_to(op, local_name_.c_str(), local_, utils::default_foreign_attributes);
+    field::belongs_to(op, remote_name_.c_str(), remote_, utils::default_foreign_attributes);
+  }
+
+  entity<LocalType> local() const { return local_; }
+  entity<LocalType> remote() const { return remote_; }
+
+private:
+  std::string local_name_;
+  std::string remote_name_;
+  sql::entity<LocalType> local_;
+  sql::entity<ForeignType> remote_;
+};
+
+}
+#endif //QUERY_HAS_MANY_TO_MANY_RELATION_HPP

include/matador/sql/noop_connection.hpp

@@ -16,7 +16,7 @@ public:
   size_t execute(const std::string &stmt) override;
   std::unique_ptr<query_result_impl> fetch(const std::string &stmt) override;
   std::unique_ptr<statement_impl> prepare(query_context context) override;
-  record describe(const std::string &table) override;
+  std::vector<sql::column_definition> describe(const std::string &table) override;
   bool exists(const std::string &schema_name, const std::string &table_name) override;
 
 private:

include/matador/sql/query.hpp

@@ -16,12 +16,9 @@ public:
 
   query_create_intermediate create();
   query_drop_intermediate drop();
-  template < class Type >
-  query_select_intermediate select();
-  template < class Type >
-  query_select_intermediate select(std::initializer_list<column> columns);
   query_select_intermediate select(std::initializer_list<column> columns);
   query_select_intermediate select(const std::vector<column>& columns);
+  query_select_intermediate select(std::vector<column> columns, std::initializer_list<column> additional_columns);
   query_insert_intermediate insert();
   query_update_intermediate update(const sql::table &table);
   query_delete_intermediate remove();
@@ -31,19 +28,5 @@ private:
   const sql::schema &schema_;
 };
 
-template<class Type>
-query_select_intermediate query::select()
-{
-  return select(column_name_generator::generate<Type>(schema_));
-}
-
-template<class Type>
-query_select_intermediate query::select(std::initializer_list<column> columns)
-{
-  auto cols = column_name_generator::generate<Type>(schema_);
-  cols.insert(cols.end(), columns);
-  return select(cols);
-}
-
 }
 #endif //QUERY_QUERY_HPP

include/matador/sql/query_context.hpp

@@ -1,7 +1,7 @@
 #ifndef QUERY_QUERY_CONTEXT_HPP
 #define QUERY_QUERY_CONTEXT_HPP
 
-#include "matador/sql/record.hpp"
+#include "matador/sql/column_definition.hpp"
 #include "matador/sql/table.hpp"
 
 namespace matador::sql {
@@ -11,7 +11,7 @@ struct query_context
   std::string sql;
   std::string command_name;
   sql::table table{""};
-  record prototype;
+  std::vector<column_definition> prototype;
   std::vector<std::string> result_vars;
   std::vector<std::string> bind_vars;
 };

include/matador/sql/query_helper.hpp

@@ -9,7 +9,7 @@
 #include <string>
 #include <ostream>
 
-#define FIELD(x) const sql::column x{this->name, #x, ""};
+#define FIELD(x) const sql::column x{*this, #x, ""};
 
 #define QUERY_HELPER(C, ...) \
 namespace matador::qh {     \

include/matador/sql/query_intermediates.hpp

@@ -2,8 +2,8 @@
 #define QUERY_QUERY_INTERMEDIATES_HPP
 
 #include "matador/sql/column_definition.hpp"
+#include "matador/sql/column_definition_generator.hpp"
 #include "matador/sql/column_generator.hpp"
-#include "matador/sql/column_name_generator.hpp"
 #include "matador/sql/key_value_generator.hpp"
 #include "matador/sql/key_value_pair.hpp"
 #include "matador/sql/placeholder_generator.hpp"
@@ -34,13 +34,13 @@ protected:
 class query_intermediate : public basic_query_intermediate
 {
 public:
-  query_intermediate(connection &db, const sql::schema &schema, query_data &data);
+  query_intermediate(connection &db, const sql::schema &schema, const std::shared_ptr<query_data> &data);
 
 protected:
-  query_data &data_;
+  std::shared_ptr<query_data> data_;
 };
 
-class query_execute_finish : public query_intermediate
+class query_execute : public query_intermediate
 {
 public:
   using query_intermediate::query_intermediate;
@@ -50,7 +50,7 @@ public:
   [[nodiscard]] query_context build() const;
 };
 
-class query_select_finish : public query_intermediate
+class query_select : public query_intermediate
 {
 protected:
   using query_intermediate::query_intermediate;
@@ -61,13 +61,29 @@ public:
   {
     return query_result<Type>(fetch());
   }
-
   query_result<record> fetch_all();
-  record fetch_one();
+
-  template<typename Type>
+  template < class Type >
-  Type fetch_value()
+  std::unique_ptr<Type> fetch_one()
   {
-    return fetch_one().at(0).as<Type>();
+    auto result = query_result<Type>(fetch());
+    auto first = result.begin();
+    if (first == result.end()) {
+      return nullptr;
+    }
+
+    return std::unique_ptr<Type>{first.release()};
+  }
+  std::optional<record> fetch_one();
+
+  template<typename Type>
+  std::optional<Type> fetch_value()
+  {
+    const auto result = fetch_one();
+    if (result.has_value()) {
+      return result.value().at(0).as<Type>().value();
+    }
+    return std::nullopt;
   }
 
   statement prepare();
@@ -80,36 +96,36 @@ private:
 
 class query_offset_intermediate;
 
-class query_limit_intermediate : public query_select_finish
+class query_limit_intermediate : public query_select
 {
 public:
-  using query_select_finish::query_select_finish;
+  using query_select::query_select;
 
   query_offset_intermediate offset(size_t offset);
 };
 
-class query_offset_intermediate : public query_select_finish
+class query_offset_intermediate : public query_select
 {
 public:
-  using query_select_finish::query_select_finish;
+  using query_select::query_select;
 
   query_limit_intermediate limit(size_t limit);
 };
 
-class query_order_direction_intermediate : public query_select_finish
+class query_order_direction_intermediate : public query_select
 {
 public:
-  using query_select_finish::query_select_finish;
+  using query_select::query_select;
 
   query_limit_intermediate limit(size_t limit);
 };
 
 class query_order_by_intermediate;
 
-class query_group_by_intermediate : public query_select_finish
+class query_group_by_intermediate : public query_select
 {
 public:
-  using query_select_finish::query_select_finish;
+  using query_select::query_select;
 
   query_order_by_intermediate order_by(const column &col);
 };
@@ -123,10 +139,10 @@ public:
   query_order_direction_intermediate desc();
 };
 
-class query_where_intermediate : public query_select_finish
+class query_where_intermediate : public query_select
 {
 public:
-  using query_select_finish::query_select_finish;
+  using query_select::query_select;
 
   query_group_by_intermediate group_by(const column &col);
   query_order_by_intermediate order_by(const column &col);
@@ -134,17 +150,30 @@ public:
 
 class query_join_intermediate;
 
-class query_on_intermediate : public query_select_finish
+struct join_data
+{
+  table join_table;
+  std::unique_ptr<basic_condition> condition;
+};
+
+class query_from_intermediate : public query_select
 {
 public:
-  using query_select_finish::query_select_finish;
+  using query_select::query_select;
 
   query_join_intermediate join_left(const table &t);
+  query_from_intermediate join_left(join_data &data);
+  query_from_intermediate join_left(std::vector<join_data> &data_vector);
+
   template<class Condition>
   query_where_intermediate where(const Condition &cond)
   {
     return where_clause(std::make_unique<Condition>(std::move(cond)));
   }
+  query_where_intermediate where(std::unique_ptr<basic_condition> &&cond)
+  {
+    return where_clause(std::move(cond));
+  }
   query_group_by_intermediate group_by(const column &col);
   query_order_by_intermediate order_by(const column &col);
 
@@ -152,6 +181,8 @@ private:
   query_where_intermediate where_clause(std::unique_ptr<basic_condition> &&cond);
 };
 
+using query_on_intermediate = query_from_intermediate;
+
 class query_join_intermediate : public query_intermediate
 {
 public:
@@ -162,36 +193,22 @@ public:
   {
     return on_clause(std::make_unique<Condition>(std::move(cond)));
   }
+  query_on_intermediate on(std::unique_ptr<basic_condition> &&cond)
+  {
+    return on_clause(std::move(cond));
+  }
 
 private:
   query_on_intermediate on_clause(std::unique_ptr<basic_condition> &&cond);
 };
 
-class query_from_intermediate : public query_select_finish
-{
-public:
-  using query_select_finish::query_select_finish;
-
-  query_join_intermediate join_left(const table &t);
-  template<class Condition>
-  query_where_intermediate where(const Condition &cond)
-  {
-    return where_clause(std::make_unique<Condition>(std::move(cond)));
-  }
-  query_group_by_intermediate group_by(const column &col);
-  query_order_by_intermediate order_by(const column &col);
-
-private:
-  query_where_intermediate where_clause(std::unique_ptr<basic_condition> &&cond);
-};
-
 class query_start_intermediate : public basic_query_intermediate
 {
 public:
   explicit query_start_intermediate(connection &db, const sql::schema &schema);
 
 protected:
-  query_data data_;
+  std::shared_ptr<query_data> data_ { std::make_shared<query_data>() };
 };
 
 class query_select_intermediate : public query_start_intermediate
@@ -216,16 +233,16 @@ class query_into_intermediate : public query_intermediate
 public:
   using query_intermediate::query_intermediate;
 
-  query_execute_finish values(std::initializer_list<any_type> values);
+  query_execute values(std::initializer_list<any_type> values);
-  query_execute_finish values(std::vector<any_type> &&values);
+  query_execute values(std::vector<any_type> &&values);
   template<class Type>
-  query_execute_finish values()
+  query_execute values()
   {
     Type obj;
     return values(std::move(as_placeholder(obj)));
   }
   template<class Type>
-  query_execute_finish values(const Type &obj)
+  query_execute values(const Type &obj)
   {
     return values(std::move(value_extractor::extract(obj)));
   }
@@ -236,15 +253,12 @@ class query_create_intermediate : public query_start_intermediate
 public:
   explicit query_create_intermediate(connection &db, const sql::schema &schema);
 
-  query_execute_finish table(const sql::table &table, std::initializer_list<column_definition> columns);
+  query_execute table(const sql::table &table, std::initializer_list<column_definition> columns);
-  query_execute_finish table(const sql::table &table, const std::vector<column_definition> &columns);
+  query_execute table(const sql::table &table, const std::vector<column_definition> &columns);
   template<class Type>
-  query_execute_finish table(const sql::table &table)
+  query_execute table(const sql::table &table)
   {
-//    if (!schema_.exists<Type>()) {
+    return this->table(table, column_definition_generator::generate<Type>(schema_));
-//      schema_.attach<Type>(table.name);
-//    }
-    return this->table(table, column_generator::generate<Type>(schema_));
   }
 };
 
@@ -253,7 +267,7 @@ class query_drop_intermediate : query_start_intermediate
 public:
   explicit query_drop_intermediate(connection &db, const sql::schema &schema);
 
-  query_execute_finish table(const sql::table &table);
+  query_execute table(const sql::table &table);
 };
 
 class query_insert_intermediate : public query_start_intermediate
@@ -263,25 +277,21 @@ public:
 
   query_into_intermediate into(const sql::table &table, std::initializer_list<column> column_names);
   query_into_intermediate into(const sql::table &table, std::vector<column> &&column_names);
-  template<class Type>
+  query_into_intermediate into(const sql::table &table);
-  query_into_intermediate into(const sql::table &table)
-  {
-    return into(table, column_name_generator::generate<Type>(schema_));
-  }
 };
 
-class query_execute_where_intermediate : public query_execute_finish
+class query_execute_where_intermediate : public query_execute
 {
 public:
-  using query_execute_finish::query_execute_finish;
+  using query_execute::query_execute;
 
   query_order_by_intermediate order_by(const column &col);
 };
 
-class query_set_intermediate : public query_execute_finish
+class query_set_intermediate : public query_execute
 {
 public:
-  using query_execute_finish::query_execute_finish;
+  using query_execute::query_execute;
 
   template<class Condition>
   query_execute_where_intermediate where(const Condition &cond)
@@ -307,10 +317,10 @@ public:
   }
 };
 
-class query_delete_from_intermediate : public query_execute_finish
+class query_delete_from_intermediate : public query_execute
 {
 public:
-  using query_execute_finish::query_execute_finish;
+  using query_execute::query_execute;
 
   template<class Condition>
   query_execute_where_intermediate where(const Condition &cond)

include/matador/sql/query_result.hpp

@@ -8,6 +8,8 @@
 
 namespace matador::sql {
 
+class record;
+
 template < typename Type >
 class query_result;
 
@@ -107,13 +109,13 @@ private:
 namespace detail {
 
 template < typename Type >
-Type* create_prototype(const record &/*prototype*/)
+Type* create_prototype(const std::vector<column_definition> &/*prototype*/)
 {
   return new Type{};
 }
 
 template <>
-record* create_prototype<record>(const record &prototype);
+record* create_prototype<record>(const std::vector<column_definition> &prototype);
 
 }
 
@@ -128,7 +130,7 @@ public:
   explicit query_result(std::unique_ptr<query_result_impl> impl)
   : impl_(std::move(impl)) {}
 
-  query_result(std::unique_ptr<query_result_impl> impl, record record_prototype)
+  query_result(std::unique_ptr<query_result_impl> impl, std::vector<column_definition> record_prototype)
   : record_prototype_(std::move(record_prototype))
   , impl_(std::move(impl)) {}
 
@@ -151,7 +153,7 @@ private:
   }
 
 private:
-  record record_prototype_;
+  std::vector<column_definition> record_prototype_;
   std::unique_ptr<query_result_impl> impl_;
 };
 

include/matador/sql/query_result_impl.hpp

@@ -7,7 +7,7 @@
 
 #include "matador/sql/any_type.hpp"
 #include "matador/sql/query_result_reader.hpp"
-#include "matador/sql/record.hpp"
+#include "matador/sql/column_definition.hpp"
 #include "matador/sql/data_type_traits.hpp"
 
 #include <memory>
@@ -15,6 +15,8 @@
 
 namespace matador::sql {
 
+class value;
+
 namespace detail {
 class pk_reader
 {
@@ -41,9 +43,11 @@ public:
   void on_has_one(const char * /*id*/, Pointer &/*x*/, const utils::foreign_attributes &/*attr*/) {}
 
   template<class ContainerType>
-  void on_has_many(const char *, ContainerType &, const char *, const char *, const utils::foreign_attributes &/*attr*/) {}
+  void on_has_many(ContainerType &, const char *, const utils::foreign_attributes &/*attr*/) {}
   template<class ContainerType>
-  void on_has_many(const char *, ContainerType &, const utils::foreign_attributes &/*attr*/) {}
+  void on_has_many_to_many(const char *id, ContainerType &c, const char *join_column, const char *inverse_join_column, const utils::foreign_attributes &/*attr*/) {}
+  template<class ContainerType>
+  void on_has_many_to_many(const char *id, ContainerType &c, const utils::foreign_attributes &/*attr*/) {}
 
 private:
   size_t column_index_{};
@@ -55,7 +59,7 @@ private:
 class query_result_impl
 {
 public:
-  query_result_impl(std::unique_ptr<query_result_reader> &&reader, record prototype);
+  query_result_impl(std::unique_ptr<query_result_reader> &&reader, std::vector<column_definition> prototype);
 
   template<typename ValueType>
   void on_primary_key(const char *id, ValueType &value, typename std::enable_if<std::is_integral<ValueType>::value && !std::is_same<bool, ValueType>::value>::type* = 0)
@@ -72,23 +76,31 @@ public:
   }
   void on_attribute(const char *id, char *value, const utils::field_attributes &attr = utils::null_attributes);
   void on_attribute(const char *id, std::string &value, const utils::field_attributes &attr = utils::null_attributes);
-  void on_attribute(const char *id, any_type &value, data_type_t type, const utils::field_attributes &attr = utils::null_attributes);
+  void on_attribute(const char *id, value &val, const utils::field_attributes &attr = utils::null_attributes);
 
   template < class Pointer >
-  void on_belongs_to(const char * /*id*/, Pointer &x, const utils::foreign_attributes &/*attr*/)
+  void on_belongs_to(const char * /*id*/, Pointer &x, const utils::foreign_attributes &attr)
   {
     if (!x.get()) {
       x.reset(new typename Pointer::value_type);
     }
+    if (attr.fetch() == utils::fetch_type::LAZY) {
       pk_reader_.read(*x, column_index_++);
+    } else {
+      utils::access::process(*this, *x);
+    }
   }
   template < class Pointer >
-  void on_has_one(const char * /*id*/, Pointer &x, const utils::foreign_attributes &/*attr*/)
+  void on_has_one(const char * /*id*/, Pointer &x, const utils::foreign_attributes &attr)
   {
     if (!x.get()) {
       x.reset(new typename Pointer::value_type);
     }
+    if (attr.fetch() == utils::fetch_type::LAZY) {
       pk_reader_.read(*x, column_index_++);
+    } else {
+      utils::access::process(*this, *x);
+    }
   }
 
   template<class ContainerType>
@@ -110,11 +122,11 @@ public:
     return true;
   }
 
-  [[nodiscard]] const record& prototype() const;
+  [[nodiscard]] const std::vector<column_definition>& prototype() const;
 
 protected:
   size_t column_index_ = 0;
-  record prototype_;
+  std::vector<column_definition> prototype_;
   std::unique_ptr<query_result_reader> reader_;
   detail::pk_reader pk_reader_;
 };

include/matador/sql/query_result_reader.hpp

@@ -6,6 +6,8 @@
 
 namespace matador::sql {
 
+class value;
+
 class query_result_reader
 {
 public:
@@ -34,7 +36,7 @@ public:
   virtual void read_value(const char *id, size_t index, std::string &value);
   virtual void read_value(const char *id, size_t index, std::string &value, size_t s);
   virtual void read_value(const char *id, size_t index, utils::blob &value);
-  virtual void read_value(const char *id, size_t index, any_type &value, data_type_t type, size_t size);
+  virtual void read_value(const char *id, size_t index, value &val, size_t size);
 };
 
 }

include/matador/sql/record.hpp

@@ -3,7 +3,7 @@
 
 #include "matador/utils/access.hpp"
 
-#include "matador/sql/column_definition.hpp"
+#include "matador/sql/field.hpp"
 
 #include <vector>
 #include <unordered_map>
@@ -15,17 +15,18 @@ struct column;
 class record
 {
 private:
-  using column_by_index = std::vector<column_definition>;
+  using field_ref = std::reference_wrapper<field>;
-  using column_index_pair = std::pair<std::reference_wrapper<column_definition>, size_t>;
+  using field_by_index = std::vector<field_ref>;
-  using column_by_name_map = std::unordered_map<std::string, column_index_pair>;
+  using field_index_pair = std::pair<field, field_by_index::difference_type>;
+  using field_by_name_map = std::unordered_map<std::string, field_index_pair>;
 
 public:
-  using iterator = column_by_index::iterator;
+  using iterator = field_by_index::iterator;
-  using const_iterator = column_by_index::const_iterator;
+  using const_iterator = field_by_index::const_iterator;
 
   record() = default;
-  record(std::initializer_list<column_definition> columns);
+  record(std::initializer_list<field> columns);
-  explicit record(const std::vector<column_definition> &columns);
+  explicit record(const std::vector<field> &columns);
   record(const record &x);
   record& operator=(const record &x);
   record(record&&) noexcept = default;
@@ -35,26 +36,17 @@ public:
   template<class Operator>
   void process(Operator &op)
   {
-    for(auto &col : columns_) {
+    for(auto &f : fields_) {
-      col.process(op);
+      f.get().process(op);
     }
   }
-  template < typename Type >
-  void append(const std::string &name, long size = -1)
-  {
-    append(make_column<Type>(name, size));
-  }
 
-  void append(column_definition col);
+  void append(const field &col);
 
-  [[nodiscard]] bool has_primary_key() const;
+  [[nodiscard]] const std::vector<field_ref>& columns() const;
-  [[nodiscard]] const column_definition& primary_key() const;
 
-  [[nodiscard]] const std::vector<column_definition>& columns() const;
+  [[nodiscard]] const field& at(const column &col) const;
-
+  [[nodiscard]] const field& at(size_t index) const;
-  [[nodiscard]] const column_definition& at(const column &col) const;
-//  [[nodiscard]] const column_definition& at(const std::string &name) const;
-  [[nodiscard]] const column_definition& at(size_t index) const;
 
   iterator find(const std::string &column_name);
   [[nodiscard]] const_iterator find(const std::string &column_name) const;
@@ -71,17 +63,17 @@ public:
   [[nodiscard]] bool empty() const;
   void clear();
 
-  [[nodiscard]] bool unknown() const;
+//  [[nodiscard]] bool unknown() const;
 
 private:
   void init();
-  void add_to_map(column_definition &col, size_t index);
+  void add_to_map(field &col, size_t index);
 
 private:
-  column_by_index columns_;
+  field_by_index fields_;
-  column_by_name_map columns_by_name_;
+  field_by_name_map fields_by_name_;
 
-  int pk_index_{-1};
+//  int pk_index_{-1};
 };
 
 }

include/matador/sql/schema.hpp

@@ -1,8 +1,8 @@
 #ifndef QUERY_SCHEMA_HPP
 #define QUERY_SCHEMA_HPP
 
-#include "matador/sql/column_generator.hpp"
+#include "matador/sql/column_definition_generator.hpp"
-#include "matador/sql/record.hpp"
+#include "matador/sql/table_definition.hpp"
 
 #include <optional>
 #include <string>
@@ -16,15 +16,14 @@ class connection;
 struct table_info
 {
   std::string name;
-  record prototype;
+  table_definition prototype;
-  void create(connection &conn, schema &scm) const;
-  void drop(connection &conn, schema &scm) const;
 };
 
 class schema
 {
 public:
   using repository = std::unordered_map<std::type_index, table_info>;
+  using repository_by_name = std::unordered_map<std::string, std::reference_wrapper<table_info>>;
   using iterator = repository::iterator;
   using const_iterator = repository::const_iterator;
 
@@ -37,10 +36,12 @@ public:
 
   [[nodiscard]] std::string name() const;
 
+  void create(connection &c);
+
   template<typename Type>
   const table_info& attach(const std::string &table_name)
   {
-    return attach(std::type_index(typeid(Type)), table_info{table_name, record{column_generator::generate<Type>(*this)}});
+    return attach(std::type_index(typeid(Type)), table_info{table_name, table_definition{column_definition_generator::generate<Type>(*this)}});
   }
 
   const table_info& attach(std::type_index ti, const table_info& table);
@@ -52,6 +53,7 @@ public:
   }
 
   [[nodiscard]] std::optional<table_info> info(std::type_index ti) const;
+  [[nodiscard]] std::optional<table_info> info(const std::string &name) const;
 
   template<typename Type>
   [[nodiscard]] std::pair<std::string, std::string> reference() const
@@ -79,6 +81,7 @@ public:
 private:
   std::string name_;
   repository repository_;
+  repository_by_name repository_by_name_;
 };
 
 }

include/matador/sql/session.hpp

@@ -4,6 +4,7 @@
 #include "matador/sql/connection.hpp"
 #include "matador/sql/connection_pool.hpp"
 #include "matador/sql/entity.hpp"
+#include "matador/sql/entity_query_builder.hpp"
 #include "matador/sql/statement.hpp"
 #include "matador/sql/schema.hpp"
 
@@ -13,6 +14,14 @@ namespace matador::sql {
 
 class dialect;
 
+enum class session_error {
+  Ok = 0,
+  NoConnectionAvailable,
+  UnknownType,
+  FailedToBuildQuery,
+  FailedToFindObject
+};
+
 class session
 {
 public:
@@ -31,6 +40,71 @@ public:
     return insert(new Type(std::forward<Args>(args)...));
   }
 
+  template<typename Type, typename PrimaryKeyType>
+  utils::result<entity<Type>, session_error> find(const PrimaryKeyType &pk) {
+    auto c = pool_.acquire();
+    if (!c.valid()) {
+      return utils::error(session_error::NoConnectionAvailable);
+    }
+    auto info = schema_->info<Type>();
+    if (!info) {
+      return utils::error(session_error::UnknownType);
+    }
+
+    entity_query_builder eqb(*schema_);
+    auto data = eqb.build<Type>(pk);
+    if (!data.is_ok()) {
+      return utils::error(session_error::FailedToBuildQuery);
+    }
+
+    auto obj = build_select_query(c, data.release()).template fetch_one<Type>();
+
+    if (!obj) {
+      return utils::error(session_error::FailedToFindObject);
+    }
+    return utils::ok(entity<Type>{ obj.release() });
+  }
+
+  template<typename Type>
+  utils::result<query_result<Type>, session_error> find() {
+    auto c = pool_.acquire();
+    if (!c.valid()) {
+      return utils::error(session_error::NoConnectionAvailable);
+    }
+    auto info = schema_->info<Type>();
+    if (!info) {
+      return utils::error(session_error::UnknownType);
+    }
+
+    entity_query_builder eqb(*schema_);
+    auto data = eqb.build<Type>();
+    if (!data.is_ok()) {
+      return utils::error(session_error::FailedToBuildQuery);
+    }
+
+    return utils::ok(build_select_query(c, data.release()).template fetch_all<Type>());
+  }
+
+  template<typename Type>
+  utils::result<query_from_intermediate, session_error> select() {
+    auto c = pool_.acquire();
+    if (!c.valid()) {
+      return utils::error(session_error::NoConnectionAvailable);
+    }
+    auto info = schema_->info<Type>();
+    if (!info) {
+      return utils::error(session_error::UnknownType);
+    }
+
+    entity_query_builder eqb(*schema_);
+    auto data = eqb.build<Type>();
+    if (!data.is_ok()) {
+      return utils::error(session_error::FailedToBuildQuery);
+    }
+
+    return utils::ok(build_select_query(c, data.release()).template fetch_all<Type>());
+  }
+
   template<typename Type>
   void drop_table();
   void drop_table(const std::string &table_name);
@@ -40,24 +114,24 @@ public:
   [[nodiscard]] size_t execute(const std::string &sql) const;
   statement prepare(query_context q) const;
 
-  record describe_table(const std::string &table_name) const;
+  std::vector<sql::column_definition> describe_table(const std::string &table_name) const;
   bool table_exists(const std::string &table_name) const;
 
-  [[nodiscard]] const schema& tables() const;
-
   const class dialect& dialect() const;
 
 private:
-  friend class query_select_finish;
+  friend class query_select;
 
   [[nodiscard]] std::unique_ptr<query_result_impl> fetch(const std::string &sql) const;
 
+  query_select build_select_query(connection_ptr<connection> &conn, entity_query_data &&data) const;
+
 private:
   connection_pool<connection> &pool_;
   const class dialect &dialect_;
 
   std::unique_ptr<schema> schema_;
-  mutable std::unordered_map<std::string, record> prototypes_;
+  mutable std::unordered_map<std::string, table_definition> prototypes_;
 };
 
 template<typename Type>
@@ -74,7 +148,11 @@ entity<Type> session::insert(Type *obj)
   if (!info) {
     return {};
   }
-  c->query(*schema_).insert().into<Type>(info->name).values(*obj).execute();
+  c->query(*schema_)
+    .insert()
+    .into(info->name, column_generator::generate<Type>(*schema_, true))
+    .values(*obj)
+    .execute();
 
   return entity{obj};
 }

include/matador/sql/table.hpp

@@ -1,26 +1,39 @@
 #ifndef QUERY_TABLE_HPP
 #define QUERY_TABLE_HPP
 
+#include "matador/sql/column.hpp"
+
 #include <typeindex>
 #include <string>
+#include <vector>
 
 namespace matador::sql {
 
 struct table
 {
-  std::string name;
-  std::string alias;
-
   table(const char *name, std::string as = "") // NOLINT(*-explicit-constructor)
   : name(name), alias(std::move(as)) {}
   table(std::string name, std::string as = "") // NOLINT(*-explicit-constructor)
-  : name(std::move(name)), alias(std::move(as)) {}
+  : name(std::move(name))
+  , alias(std::move(as)) {}
+  table(std::string name, std::string as, const std::vector<column> &columns)
+  : name(std::move(name))
+  , alias(std::move(as))
+  , columns(columns) {}
 
   table& as(const std::string &a) {
     alias = a;
     return *this;
   }
 
+  [[nodiscard]] table as(const std::string &a) const {
+    return { name, a, columns };
+  }
+
+  std::string name;
+  std::string alias;
+
+  std::vector<column> columns;
 };
 
 }

include/matador/sql/table_definition.hpp

@@ -0,0 +1,73 @@
+#ifndef QUERY_TABLE_DEFINITION_HPP
+#define QUERY_TABLE_DEFINITION_HPP
+
+#include "matador/sql/column.hpp"
+#include "matador/sql/column_definition.hpp"
+
+#include <unordered_map>
+
+namespace matador::sql {
+
+class table_definition final
+{
+private:
+  using column_by_index = std::vector<column_definition>;
+  using column_index_pair = std::pair<std::reference_wrapper<column_definition>, column_by_index::difference_type>;
+  using column_by_name_map = std::unordered_map<std::string, column_index_pair>;
+
+public:
+  using iterator = column_by_index::iterator;
+  using const_iterator = column_by_index::const_iterator;
+
+  table_definition() = default;
+  table_definition(std::initializer_list<column_definition> columns);
+  explicit table_definition(const std::vector<column_definition> &columns);
+  table_definition(const table_definition &x);
+  table_definition& operator=(const table_definition &x);
+  table_definition(table_definition&&) noexcept = default;
+  table_definition& operator=(table_definition&&) noexcept = default;
+  ~table_definition() = default;
+
+  [[nodiscard]] bool has_primary_key() const;
+  [[nodiscard]] std::optional<column_definition> primary_key() const;
+
+  template < typename Type >
+  void append(const std::string &name, long size = -1)
+  {
+    append(make_column<Type>(name, size));
+  }
+  void append(column_definition col);
+
+  [[nodiscard]] const std::vector<column_definition>& columns() const;
+
+  [[nodiscard]] const column_definition& at(const column &col) const;
+  [[nodiscard]] const column_definition& at(size_t index) const;
+
+  iterator find(const std::string &column_name);
+  [[nodiscard]] const_iterator find(const std::string &column_name) const;
+
+  iterator begin();
+  [[nodiscard]] const_iterator begin() const;
+  [[nodiscard]] const_iterator cbegin() const;
+
+  iterator end();
+  [[nodiscard]] const_iterator end() const;
+  [[nodiscard]] const_iterator cend() const;
+
+  [[nodiscard]] size_t size() const;
+  [[nodiscard]] bool empty() const;
+  void clear();
+
+private:
+  void init();
+  void add_to_map(column_definition &col, size_t index);
+
+private:
+  column_by_index columns_;
+  column_by_name_map columns_by_name_;
+
+  int pk_index_{-1};
+};
+
+}
+#endif //QUERY_TABLE_DEFINITION_HPP

include/matador/sql/value.hpp

@@ -0,0 +1,81 @@
+#ifndef QUERY_VALUE_HPP
+#define QUERY_VALUE_HPP
+
+#include "matador/sql/any_type.hpp"
+#include "matador/sql/any_type_to_visitor.hpp"
+#include "matador/sql/data_type_traits.hpp"
+
+#include "matador/utils/types.hpp"
+
+#include <optional>
+
+namespace matador::sql {
+
+namespace detail {
+template<typename Type>
+size_t determine_size(const Type &/*val*/)
+{
+  return 0;
+}
+size_t determine_size(const std::string &val);
+size_t determine_size(const char *val);
+size_t determine_size(const utils::blob &val);
+
+}
+class value
+{
+public:
+  value() = default;
+  template<typename Type>
+  explicit value(Type value, size_t size = 0)
+  : size_(size)
+  , value_(value)
+  , type_(data_type_traits<Type>::builtin_type(size)) {}
+  explicit value(data_type_t data_type, size_t size = 0);
+  value(const value &x) = default;
+  value& operator=(const value &x) = default;
+  template<typename Type>
+  value& operator=(Type val)
+  {
+    value_ = val;
+    size_ = detail::determine_size(val);
+    type_ = data_type_traits<Type>::builtin_type(size_);
+    return *this;
+  }
+  value(value &&x) noexcept;
+  value& operator=(value &&x) noexcept;
+
+  template<class Type>
+  std::optional<Type> as() const
+  {
+    if (std::holds_alternative<Type>(value_)) {
+      return std::get<Type>(value_);
+    } else {
+      any_type_to_visitor<Type> visitor;
+      std::visit(visitor, const_cast<any_type &>(value_));
+      return visitor.result;
+    }
+  }
+  [[nodiscard]] std::string str() const;
+
+  [[nodiscard]] size_t size() const;
+  [[nodiscard]] data_type_t type() const;
+
+  [[nodiscard]] bool is_integer() const;
+  [[nodiscard]] bool is_floating_point() const;
+  [[nodiscard]] bool is_bool() const;
+  [[nodiscard]] bool is_string() const;
+  [[nodiscard]] bool is_varchar() const;
+  [[nodiscard]] bool is_blob() const;
+  [[nodiscard]] bool is_null() const;
+  [[nodiscard]] bool is_unknown() const;
+
+private:
+  any_type value_;
+  size_t size_{};
+  data_type_t type_{data_type_t::type_unknown};
+
+};
+
+}
+#endif //QUERY_VALUE_HPP

include/matador/sql/value_extractor.hpp

@@ -53,9 +53,11 @@ public:
     values_.emplace_back(fk_value_extractor_.extract(*x));
   }
   template<class ContainerType>
-  void on_has_many(const char *, ContainerType &, const char *, const char *, const utils::foreign_attributes &/*attr*/) {}
+  void on_has_many(ContainerType &, const char *, const utils::foreign_attributes &/*attr*/) {}
   template<class ContainerType>
-  void on_has_many(const char *, ContainerType &, const utils::foreign_attributes &/*attr*/) {}
+  void on_has_many_to_many(const char *id, ContainerType &c, const char *join_column, const char *inverse_join_column, const utils::foreign_attributes &/*attr*/) {}
+  template<class ContainerType>
+  void on_has_many_to_many(const char *id, ContainerType &c, const utils::foreign_attributes &/*attr*/) {}
 
 private:
   template<typename Type>

include/matador/utils/access.hpp

@@ -64,24 +64,19 @@ void belongs_to(Operator &op, const char *id, Type &value, const foreign_attribu
   op.on_belongs_to(id, value, attr);
 }
 
-//template<class Operator, class Type, template<class ...> class ContainerType>
-//void has_many(Operator &op, const char *id, container<Type, ContainerType> &container, const foreign_attributes &attr) {
-//  op.on_has_many(id, container, attr);
-//}
-
 template<class Operator, class Type, template<class ...> class ContainerType>
-void has_many(Operator &op, const char *id, ContainerType<Type> &container, const foreign_attributes &attr) {
+void has_many(Operator &op, ContainerType<Type> &container, const char *join_column, const foreign_attributes &attr) {
-  op.on_has_many(id, container, attr);
+  op.on_has_many(container, join_column, attr);
 }
 
-//template<class Operator, class Type, template<class ...> class ContainerType>
+template<class Operator, class Type, template<class ...> class ContainerType>
-//void has_many(Operator &op, const char *id, container<Type, ContainerType> &container, const char *left_column, const char *right_column, const foreign_attributes &attr) {
+void has_many_to_many(Operator &op, const char *id, ContainerType<Type> &container, const char *join_column, const char *inverse_join_column, const foreign_attributes &attr) {
-//  op.on_has_many(id, container, left_column, right_column, attr);
+  op.on_has_many_to_many(id, container, join_column, inverse_join_column, attr);
-//}
+}
 
 template<class Operator, class Type, template<class ...> class ContainerType>
-void has_many(Operator &op, const char *id, ContainerType<Type> &container, const char *left_column, const char *right_column, const foreign_attributes &attr) {
+void has_many_to_many(Operator &op, const char *id, ContainerType<Type> &container, const foreign_attributes &attr) {
-  op.on_has_many(id, container, left_column, right_column, attr);
+  op.on_has_many_to_many(id, container, attr);
 }
 
 }

include/matador/utils/result.hpp

@@ -0,0 +1,113 @@
+#ifndef QUERY_RESULT_HPP
+#define QUERY_RESULT_HPP
+
+#include <variant>
+
+namespace matador::utils {
+
+template < typename ValueType, typename ErrorType >
+class [[nodiscard]] result;
+
+template <typename ValueType>
+struct is_result : std::false_type {};
+
+template < typename ValueType, typename ErrorType >
+struct is_result<result<ValueType, ErrorType>> : std::true_type {};
+
+template < typename ValueType >
+class ok
+{
+public:
+  using value_type = ValueType;
+  explicit constexpr ok(const ValueType &value) : value_(value) {}
+  explicit constexpr ok(ValueType &&value) : value_(std::move(value)) {}
+
+  constexpr ValueType&& release() { return std::move(value_); }
+  const ValueType& value() const { return value_; }
+  ValueType& value() { return value_; }
+
+private:
+  ValueType value_;
+};
+
+template < typename ErrorType >
+class error
+{
+public:
+  using value_type = ErrorType;
+
+  explicit constexpr error(const ErrorType &error) : error_(error) {}
+  explicit constexpr error(ErrorType &&error) : error_(std::move(error)) {}
+
+  constexpr ErrorType&& release() { return std::move(error_); }
+  const ErrorType& value() const { return error_; }
+  ErrorType value() { return error_; }
+
+private:
+  ErrorType error_;
+};
+
+template < typename ValueType, typename ErrorType >
+class result
+{
+public:
+  using value_type = ok<ValueType>;
+  using error_type = error<ErrorType>;
+
+  result() : result_(ValueType{}) {}
+  result(value_type value) : result_(std::move(value)) {} // NOLINT(*-explicit-constructor)
+  result(error_type error) : result_(std::move(error)) {} // NOLINT(*-explicit-constructor)
+  result(const result<ValueType, ErrorType> &x) = default;
+  result& operator=(const result<ValueType, ErrorType> &x) = default;
+  result(result<ValueType, ErrorType> &&x) = default;
+  result& operator=(result<ValueType, ErrorType> &&x) = default;
+
+  operator bool() const { return is_ok(); } // NOLINT(*-explicit-constructor)
+
+  [[nodiscard]] bool is_ok() const { return std::holds_alternative<value_type>(result_); }
+  [[nodiscard]] bool is_error() const { return std::holds_alternative<error_type>(result_); }
+
+  ValueType&& release() { return std::get<value_type>(result_).release(); }
+  ErrorType&& release_error() { return std::get<error_type>(result_).release(); }
+
+  const ValueType& value() const { return std::get<value_type>(result_).value(); }
+  const ErrorType& err() const { return std::get<error_type>(result_).value(); }
+  ErrorType err() { return std::get<error_type>(result_).value(); }
+
+  constexpr const ValueType* operator->() const { return &value(); }
+  constexpr ValueType* operator->() { return &std::get<value_type>(result_).value(); }
+
+  template<typename Func, typename SecondValueType = typename std::invoke_result_t<Func, ValueType >>
+  result<SecondValueType, ErrorType> transform(Func &&f) {
+    if (is_ok()) {
+      return result<SecondValueType, ErrorType>(ok(f(release())));
+    }
+
+    return result<SecondValueType, ErrorType>(error(release_error()));
+  }
+
+  template<typename Func, typename SecondValueType = typename std::invoke_result_t<Func, ValueType >::value_type::value_type>
+  result<SecondValueType, ErrorType> and_then(Func &&f) {
+    if (is_ok()) {
+      return f(release());
+    }
+
+    return result<SecondValueType, ErrorType>(error(release_error()));
+  }
+
+  template<typename Func, typename SecondErrorType = typename std::invoke_result_t<Func, ErrorType >::error_type::value_type>
+  result<ValueType, SecondErrorType> or_else(Func &&f) {
+    if (is_error()) {
+      return f(err());
+    }
+
+    return result<ValueType, SecondErrorType>(ok(release()));
+  }
+
+private:
+  std::variant<value_type, error_type> result_;
+};
+
+}
+
+#endif //QUERY_RESULT_HPP

src/CMakeLists.txt

@@ -12,8 +12,8 @@ set(SQL_SOURCES
   sql/session.cpp
   sql/backend_provider.cpp
   sql/query_result_impl.cpp
+  sql/column_definition_generator.cpp
   sql/column_generator.cpp
-  sql/column_name_generator.cpp
   sql/key_value_generator.cpp
   sql/fk_value_extractor.cpp
   sql/schema.cpp
@@ -35,6 +35,10 @@ set(SQL_SOURCES
   sql/noop_connection.cpp
   sql/query_part.cpp
   sql/any_type_to_string_visitor.cpp
+  sql/field.cpp
+  sql/table_definition.cpp
+  sql/value.cpp
+  sql/entity_query_builder.cpp
 )
 
 set(SQL_HEADER
@@ -55,8 +59,8 @@ set(SQL_HEADER
   ../include/matador/sql/session.hpp
   ../include/matador/sql/backend_provider.hpp
   ../include/matador/sql/query_result_impl.hpp
+  ../include/matador/sql/column_definition_generator.hpp
   ../include/matador/sql/column_generator.hpp
-  ../include/matador/sql/column_name_generator.hpp
   ../include/matador/sql/value_extractor.hpp
   ../include/matador/sql/any_type.hpp
   ../include/matador/sql/key_value_generator.hpp
@@ -86,28 +90,11 @@ set(SQL_HEADER
   ../include/matador/sql/query_part.hpp
   ../include/matador/sql/any_type_to_string_visitor.hpp
   ../include/matador/sql/query_helper.hpp
-)
+  ../include/matador/sql/field.hpp
-
+  ../include/matador/sql/entity_query_builder.hpp
-set(QUERY_SOURCES
+  ../include/matador/sql/table_definition.hpp
-  query/query.cpp
+  ../include/matador/sql/has_many_to_many_relation.hpp
-  query/query_compiler.cpp
+  ../include/matador/sql/value.hpp
-  query/query_parts.cpp
-  query/column.cpp
-  query/query_builder.cpp
-  query/query_intermediates.cpp
-)
-
-set(QUERY_HEADER
-  ../include/matador/query/query.hpp
-  ../include/matador/query/query_part_visitor.hpp
-  ../include/matador/query/query_compiler.hpp
-  ../include/matador/query/query_parts.hpp
-  ../include/matador/query/column.hpp
-  ../include/matador/query/query_builder.hpp
-  ../include/matador/query/query_intermediates.hpp
-  ../include/matador/query/sql_commands.hpp
-  ../include/matador/query/query_data.hpp
-  ../include/matador/query/table.hpp
 )
 
 set(UTILS_HEADER
@@ -124,6 +111,7 @@ set(UTILS_HEADER
   ../include/matador/utils/types.hpp
   ../include/matador/utils/foreign_attributes.hpp
   ../include/matador/utils/fetch_type.hpp
+  ../include/matador/utils/result.hpp
 )
 
 set(UTILS_SOURCES

src/query/column.cpp

@@ -1,21 +0,0 @@
-#include "matador/query/column.hpp"
-
-namespace matador::query {
-
-column::column(const char *name)
-: name(name) {}
-
-column::column(std::string name)
-: name(std::move(name)) {}
-
-column::column(std::string table_name, std::string name, std::string as)
-: table(std::move(table_name))
-, name(std::move(name))
-, alias(std::move(as)) {}
-
-column& column::as(std::string a) {
-  alias = std::move(a);
-  return *this;
-}
-
-}

src/query/query.cpp

@@ -1,6 +0,0 @@
-#include "matador/query/query.hpp"
-
-namespace matador::sql {
-
-
-}

src/query/query_builder.cpp

@@ -1,13 +0,0 @@
-#include "matador/query/query_builder.hpp"
-
-namespace matador::query {
-
-query_builder::query_builder(const std::shared_ptr<sql::schema> &scm)
-: schema_(scm) {}
-
-query_select_intermediate query_builder::select(std::initializer_list<column> columns)
-{
-  return query_select_intermediate{schema_};
-}
-
-}

src/query/query_compiler.cpp

@@ -1,33 +0,0 @@
-#include "matador/query/query_compiler.hpp"
-#include "matador/query/query_data.hpp"
-#include "matador/query/column.hpp"
-
-#include "matador/sql/dialect.hpp"
-
-namespace matador::query {
-
-query_compiler::query_compiler(sql::dialect &d)
-  : dialect_(d)
-{}
-
-std::string query_compiler::compile(const query_data *data)
-{
-  sql_.clear();
-  for (const auto &part : data->parts) {
-    part->accept(*this);
-  }
-
-  return sql_;
-}
-
-void query_compiler::visit(query_select_part &select_part)
-{
-  auto ci = "name"_col.as("c01");
-}
-
-void query_compiler::visit(query_from_part &from_part)
-{
-
-}
-
-}

src/query/query_intermediates.cpp

@@ -1,8 +0,0 @@
-#include "matador/query/query_intermediates.hpp"
-
-namespace matador::query {
-
-query_intermediate::query_intermediate(const std::shared_ptr<sql::schema> &scm)
-: schema_(scm) {}
-
-}

src/query/query_parts.cpp

@@ -1,30 +0,0 @@
-#include "matador/query/query_parts.hpp"
-
-namespace matador::query {
-
-query_part::query_part(sql::dialect::token_t token)
-  : token_(token) {}
-
-query_select_part::query_select_part(std::vector<column> columns)
-  : query_part(sql::dialect::token_t::SELECT)
-  , columns_(std::move(columns)) {}
-
-void query_select_part::accept(query_part_visitor &visitor)
-{
-  visitor.visit(*this);
-}
-
-query_from_part::query_from_part(std::string table_name)
-  : query_part(sql::dialect::token_t::FROM)
-  , table_(std::move(table_name)) {}
-
-query_from_part::query_from_part(std::string table_name, std::string as)
-  : query_part(sql::dialect::token_t::FROM)
-  , table_(std::move(table_name))
-  , alias_(std::move(as)) {}
-
-void query_from_part::accept(query_part_visitor &visitor)
-{
-  visitor.visit(*this);
-}
-}

src/sql/backend_provider.cpp

@@ -2,6 +2,7 @@
 #include "matador/sql/noop_connection.hpp"
 #include "matador/sql/dialect_builder.hpp"
 
+#include <algorithm>
 #include <stdexcept>
 
 namespace matador::sql {

src/sql/column.cpp

@@ -1,4 +1,5 @@
 #include "matador/sql/column.hpp"
+#include "matador/sql/table.hpp"
 
 namespace matador::sql {
 
@@ -7,4 +8,46 @@ column operator ""_col(const char *name, size_t len)
   return {{name, len}};
 }
 
+column::column(const char *name) : name(name) {}
+
+column::column(std::string name) : name(std::move(name)) {}
+
+column::column(sql_function_t func, std::string name) : name(std::move(name)), function_(func) {}
+
+column::column(std::string table_name, std::string name, std::string as)
+: table(std::move(table_name))
+, name(std::move(name))
+, alias(std::move(as)) {}
+
+column::column(std::string table_name, const char *name, std::string as)
+: table(std::move(table_name))
+, name(name)
+, alias(std::move(as)) {}
+
+column::column(struct table &t, const char *name, std::string as)
+: table(t.name)
+, name(name)
+, alias(std::move(as))
+{
+  t.columns.push_back(*this);
+}
+
+bool column::equals(const column &x) const
+{
+  return table == x.table &&
+         name == x.name &&
+         alias == x.alias &&
+         function_ == x.function_;
+}
+
+column &column::as(std::string a)
+{
+  alias = std::move(a);
+  return *this;
+}
+
+bool column::is_function() const
+{
+  return function_ != sql_function_t::NONE;
+}
 }

src/sql/column_definition.cpp

@@ -33,7 +33,7 @@ const std::string &column_definition::name() const
   return name_;
 }
 
-size_t column_definition::index() const
+int column_definition::index() const
 {
   return index_;
 }
@@ -63,6 +63,46 @@ const std::string &column_definition::ref_column() const
   return ref_column_;
 }
 
+bool column_definition::is_integer() const
+{
+  return type_ >= data_type_t::type_char && type_ <= data_type_t::type_unsigned_long_long;
+}
+
+bool column_definition::is_floating_point() const
+{
+  return type_ == data_type_t::type_float || type_ == data_type_t::type_double;
+}
+
+bool column_definition::is_bool() const
+{
+  return type_ == data_type_t::type_bool;
+}
+
+bool column_definition::is_string() const
+{
+  return type_ == data_type_t::type_text;
+}
+
+bool column_definition::is_varchar() const
+{
+  return type_ == data_type_t::type_varchar;
+}
+
+bool column_definition::is_blob() const
+{
+  return type_ == data_type_t::type_blob;
+}
+
+bool column_definition::is_null() const
+{
+  return type_ == data_type_t::type_null;
+}
+
+bool column_definition::is_unknown() const
+{
+  return type_ == data_type_t::type_unknown;
+}
+
 void column_definition::type(data_type_t type)
 {
   type_ = type;
@@ -70,6 +110,10 @@ void column_definition::type(data_type_t type)
 
 std::string column_definition::str() const
 {
+  if (std::holds_alternative<std::string>(value_)) {
+    return std::get<std::string>(value_);
+  }
+
   any_type_to_visitor<std::string> visitor;
   std::visit(visitor, const_cast<any_type &>(value_));
   return visitor.result;

src/sql/column_definition_generator.cpp

@@ -0,0 +1,31 @@
+#include "matador/sql/column_definition_generator.hpp"
+#include "matador/sql/schema.hpp"
+
+namespace matador::sql {
+
+column_definition_generator::column_definition_generator(std::vector<column_definition> &columns, const schema &repo)
+: columns_(columns)
+, repo_(repo)
+{}
+
+void column_definition_generator::on_primary_key(const char *id, std::string &pk, size_t size)
+{
+  on_attribute(id, pk, { size, utils::constraints::PRIMARY_KEY });
+}
+
+void column_definition_generator::on_revision(const char *id, unsigned long long int &x)
+{
+  on_attribute(id, x);
+}
+
+std::pair<std::string, std::string> column_definition_generator::determine_foreign_ref(const std::type_index &ti)
+{
+  return repo_.reference(ti);
+}
+
+void fk_column_generator::on_primary_key(const char *, std::string &, size_t size)
+{
+  type_ = data_type_traits<std::string>::builtin_type(size);
+}
+
+}

src/sql/column_generator.cpp

@@ -1,31 +1,33 @@
 #include "matador/sql/column_generator.hpp"
-#include "matador/sql/schema.hpp"
 
 namespace matador::sql {
 
-column_generator::column_generator(std::vector<column_definition> &columns, const schema &repo)
+column_generator::column_generator(std::vector<column> &column_infos,
-: columns_(columns)
+                                   const sql::schema &ts,
-, repo_(repo)
+                                   const std::string &table_name,
-{}
+                                   bool force_lazy)
-
+: column_infos_(column_infos)
-void column_generator::on_primary_key(const char *id, std::string &pk, size_t size)
+, table_schema_(ts)
+, force_lazy_(force_lazy)
 {
-  on_attribute(id, pk, { size, utils::constraints::PRIMARY_KEY });
+  table_name_stack_.push(table_name);
 }
 
-void column_generator::on_revision(const char *id, unsigned long long int &x)
+void column_generator::on_primary_key(const char *id, std::string &, size_t)
 {
-  on_attribute(id, x);
+  push(id);
 }
 
-std::pair<std::string, std::string> column_generator::determine_foreign_ref(const std::type_index &ti)
+void column_generator::on_revision(const char *id, unsigned long long int &)
 {
-  return repo_.reference(ti);
+  push(id);
 }
 
-void fk_column_generator::on_primary_key(const char *, std::string &, size_t size)
+void column_generator::push(const std::string &column_name)
 {
-  type_ = data_type_traits<std::string>::builtin_type(size);
+  char str[4];
+  snprintf(str, 4, "c%02d", ++column_index);
+  column_infos_.emplace_back(table_name_stack_.top(), column_name, str);
 }
 
 }

src/sql/column_name_generator.cpp

@@ -1,31 +0,0 @@
-#include "matador/sql/column_name_generator.hpp"
-
-namespace matador::sql {
-
-column_name_generator::column_name_generator(std::vector<column> &column_infos,
-                                             const sql::schema &ts,
-                                             const std::string &table_name)
-: column_infos_(column_infos)
-, table_schema_(ts)
-{
-  table_name_stack_.push(table_name);
-}
-
-void column_name_generator::on_primary_key(const char *id, std::string &, size_t)
-{
-  push(id);
-}
-
-void column_name_generator::on_revision(const char *id, unsigned long long int &)
-{
-  push(id);
-}
-
-void column_name_generator::push(const std::string &column_name)
-{
-  char str[4];
-  snprintf(str, 4, "c%02d", ++column_index);
-  column_infos_.emplace_back(table_name_stack_.top(), column_name, str);
-}
-
-}

src/sql/condition.cpp

@@ -1,28 +1,46 @@
 #include "matador/sql/condition.hpp"
 
+#include "matador/sql/query_intermediates.hpp"
+
 namespace matador::sql {
 
 condition<column, placeholder, std::enable_if<true>::type>::condition(const column &fld, basic_condition::operand_t op, const placeholder &val)
 : basic_column_condition(fld, op), value(val)
 {}
 
-std::string condition<column, placeholder, std::enable_if<true>::type>::evaluate(dialect &d, query_context &query) const
+std::string condition<column, placeholder, std::enable_if<true>::type>::evaluate(const dialect &d, query_context &query) const
 {
   query.bind_vars.emplace_back(field_.name);
   return d.prepare_identifier(field_) + " " + operand + " " + d.next_placeholder(query.bind_vars);
 }
 
-condition<column, query_context>::condition(column col, basic_condition::operand_t op, query_context &q)
+condition<column, query_context>::condition(column col, basic_condition::operand_t op, const query_context &q)
 : basic_column_condition(std::move(col), op), query_(q)
 {}
 
-std::string condition<column, query_context>::evaluate(dialect &d, query_context &query) const
+std::string condition<column, query_context>::evaluate(const dialect &d, query_context &query) const
 {
   std::string result(d.prepare_identifier(field_) + " " + operand + " (");
-  result += (")");
+  result += query_.sql + (")");
   return result;
 }
 
+condition<column, query_context> in( const column& col, const query_context &q ) {
+    return {col, basic_condition::operand_t::IN_LIST, q};
+}
+
+condition<column, query_context> in( const column& col, const query_select& q ) {
+    return in(col, q.build());
+}
+
+condition<column, std::string> like( const column& col, const std::string& val ) {
+    return {col, basic_condition::operand_t::LIKE, val};
+}
+
+condition<column, query_context> equals( const column& col, query_context& q ) {
+    return {col, basic_condition::operand_t::EQUAL, q};
+}
+
 condition<column, column> operator==(const column &a, const column &b)
 {
   return {a, basic_condition::operand_t::EQUAL, b};

src/sql/connection.cpp

@@ -2,7 +2,9 @@
 
 #include "matador/sql/backend_provider.hpp"
 #include "matador/sql/connection_impl.hpp"
+#include "matador/sql/schema.hpp"
 
+#include <algorithm>
 #include <stdexcept>
 #include <utility>
 
@@ -68,7 +70,7 @@ const connection_info &connection::info() const
   return connection_info_;
 }
 
-record connection::describe(const std::string &table_name) const
+std::vector<sql::column_definition> connection::describe(const std::string &table_name) const
 {
   return std::move(connection_->describe(table_name));
 }
@@ -89,17 +91,26 @@ size_t connection::execute(const std::string &sql) const
   return connection_->execute(sql);
 }
 
-sql::query connection::query(const sql::schema &schema) const
+sql::query connection::query(const schema &schema) const
 {
   return sql::query(*const_cast<connection*>(this), schema);
 }
 
+bool is_unknown(const std::vector<sql::column_definition> &columns) {
+  return std::all_of(std::begin(columns), std::end(columns), [](const auto &col) {
+    return col.type() == data_type_t::type_unknown;
+  });
+}
+
 query_result<record> connection::fetch(const query_context &q) const
 {
-  if (q.prototype.empty() || q.prototype.unknown()) {
+  if (q.prototype.empty() || is_unknown(q.prototype)) {
     const auto table_prototype = describe(q.table.name);
     for (auto &col : q.prototype) {
-      if (const auto rit = table_prototype.find(col.name()); col.type() == data_type_t::type_unknown && rit != table_prototype.end()) {
+      const auto rit = std::find_if(std::begin(table_prototype), std::end(table_prototype), [&col](const auto &value) {
+        return value.name() == col.name();
+      });
+      if (col.type() == data_type_t::type_unknown && rit != table_prototype.end()) {
         const_cast<column_definition&>(col).type(rit->type());
       }
      }

src/sql/convert.cpp

@@ -59,4 +59,9 @@ long double to_double(const char *source)
   return result;
 }
 
+void convert(utils::blob &dest, const utils::blob &data)
+{
+  dest = data;
+}
+
 }

src/sql/data_type_traits.cpp

@@ -6,6 +6,21 @@
 
 namespace matador::sql {
 
+void data_type_traits<nullptr_t>::read_value(query_result_reader &reader, const char *id, size_t index, nullptr_t &/*value*/)
+{
+//  reader.read_value(id, index, value);
+}
+
+void data_type_traits<nullptr_t>::bind_value(parameter_binder &binder, size_t index, nullptr_t &/*value*/)
+{
+//  binder.bind(index, value);
+}
+
+void data_type_traits<nullptr_t>::bind_result_value(result_parameter_binder &binder, size_t index, nullptr_t &/*value*/)
+{
+//  binder.bind_result_value(index, value);
+}
+
 void data_type_traits<char>::read_value(query_result_reader &reader, const char *id, size_t index, char &value)
 {
   reader.read_value(id, index, value);

src/sql/dialect.cpp

@@ -51,8 +51,8 @@ std::string dialect::prepare_literal(const std::string &str) const
 
 void dialect::quote_identifier(std::string &str) const
 {
-  str.insert(0, token_at(token_t::START_QUOTE));
+  // str.insert(0, token_at(token_t::START_QUOTE));
-  str += token_at(token_t::END_QUOTE);
+  // str += token_at(token_t::END_QUOTE);
 }
 
 void dialect::escape_quotes_in_identifier(std::string &str) const

src/sql/entity_query_builder.cpp

@@ -0,0 +1,38 @@
+#include "matador/sql/entity_query_builder.hpp"
+
+namespace matador::sql {
+
+void entity_query_builder::on_primary_key(const char *id, std::string &, size_t)
+{
+  push(id);
+  if (!is_root_entity()) {
+    auto b = pk_.is_varchar();
+    std::cout << "is matching primary key: " << std::boolalpha << b << "\n";
+  }
+}
+
+void entity_query_builder::on_revision(const char *id, unsigned long long &/*rev*/)
+{
+  push(id);
+}
+
+void entity_query_builder::push(const std::string &column_name)
+{
+  char str[4];
+  snprintf(str, 4, "c%02d", ++column_index);
+  entity_query_data_.columns.emplace_back(table_info_stack_.top().name, column_name, str);
+}
+
+[[nodiscard]] bool entity_query_builder::is_root_entity() const {
+  return table_info_stack_.size() == 1;
+}
+
+void entity_query_builder::append_join(const column &left, const column &right)
+{
+  entity_query_data_.joins.push_back({
+                                       { right.table },
+                                       make_condition(left == right)
+                                     });
+}
+
+}

src/sql/field.cpp

@@ -0,0 +1,103 @@
+#include "matador/sql/field.hpp"
+
+#include <ostream>
+
+namespace matador::sql {
+
+field::field(std::string name)
+  : name_(std::move(name))
+  , value_(nullptr)
+{}
+
+field::field(std::string name, data_type_t data_type, size_t size, int index)
+  : name_(std::move(name))
+  , index_(index)
+  , value_(data_type, size) {}
+
+field::field(field &&x) noexcept
+  : name_(std::move(x.name_))
+  , index_(x.index_)
+  , value_(std::move(x.value_))
+{
+  x.value_ = nullptr;
+  x.index_ = -1;
+}
+
+field &field::operator=(field &&x) noexcept
+{
+  name_ = std::move(x.name_);
+  index_ = x.index_;
+  value_ = std::move(x.value_);
+  x.index_ = -1;
+  x.value_ = nullptr;
+
+  return *this;
+}
+
+const std::string &field::name() const
+{
+  return name_;
+}
+
+size_t field::size() const
+{
+  return value_.size();
+}
+
+int field::index() const
+{
+  return index_;
+}
+
+std::ostream &operator<<(std::ostream &out, const field &col)
+{
+  out << col.str();
+  return out;
+}
+
+std::string field::str() const
+{
+  return as<std::string>().value();
+}
+
+bool field::is_integer() const
+{
+  return value_.is_integer();
+}
+
+bool field::is_floating_point() const
+{
+  return value_.is_floating_point();
+}
+
+bool field::is_bool() const
+{
+  return value_.is_bool();
+}
+
+bool field::is_string() const
+{
+  return value_.is_string();
+}
+
+bool field::is_varchar() const
+{
+  return value_.is_varchar();
+}
+
+bool field::is_blob() const
+{
+  return value_.is_blob();
+}
+
+bool field::is_null() const
+{
+  return value_.is_null();
+}
+
+bool field::is_unknown() const
+{
+  return value_.is_unknown();
+}
+
+}

src/sql/noop_connection.cpp

@@ -39,7 +39,7 @@ std::unique_ptr<statement_impl> noop_connection::prepare(query_context context)
   return {};
 }
 
-record noop_connection::describe(const std::string &table)
+std::vector<sql::column_definition> noop_connection::describe(const std::string &table)
 {
   return {};
 }

src/sql/query.cpp

@@ -28,6 +28,14 @@ query_select_intermediate query::select(const std::vector<column>& columns)
   return {connection_, schema_, columns};
 }
 
+query_select_intermediate query::select(std::vector<column> columns, std::initializer_list<column> additional_columns)
+{
+  for (const auto &col : additional_columns) {
+    columns.push_back(col);
+  }
+  return {connection_, schema_, columns};
+}
+
 query_insert_intermediate query::insert()
 {
   return query_insert_intermediate{connection_, schema_};

src/sql/query_builder.cpp

@@ -1,5 +1,5 @@
 #include "matador/sql/query_builder.hpp"
-#include "matador/sql/column_name_generator.hpp"
+#include "matador/sql/column_generator.hpp"
 #include "matador/sql/column.hpp"
 #include "matador/sql/dialect.hpp"
 
@@ -141,18 +141,18 @@ query_builder &query_builder::select(const std::vector<column> &columns)
     for (const auto &col: columns) {
       result.append(dialect_.prepare_identifier(col));
       query_.result_vars.emplace_back(col.name);
-      query_.prototype.append(column_definition{col.name});
+      query_.prototype.emplace_back(col.name);
     }
   } else {
     auto it = columns.begin();
     result.append(dialect_.prepare_identifier(*it));
     query_.result_vars.emplace_back(it->name);
-    query_.prototype.append(column_definition{(*it++).name});
+    query_.prototype.emplace_back((*it++).name);
     for (; it != columns.end(); ++it) {
       result.append(", ");
       result.append(dialect_.prepare_identifier(*it));
       query_.result_vars.emplace_back(it->name);
-      query_.prototype.append(column_definition{(*it).name});
+      query_.prototype.emplace_back((*it).name);
     }
   }
 

src/sql/query_compiler.cpp

@@ -33,18 +33,18 @@ void query_compiler::visit(query_select_part &select_part)
     for (const auto &col: columns) {
       result.append(dialect_.prepare_identifier(col));
       query_.result_vars.emplace_back(col.name);
-      query_.prototype.append(column_definition{col.name});
+      query_.prototype.emplace_back(col.name);
     }
   } else {
     auto it = columns.begin();
     result.append(dialect_.prepare_identifier(*it));
     query_.result_vars.emplace_back(it->name);
-    query_.prototype.append(column_definition{(*it++).name});
+    query_.prototype.emplace_back((*it++).name);
     for (; it != columns.end(); ++it) {
       result.append(", ");
       result.append(dialect_.prepare_identifier(*it));
       query_.result_vars.emplace_back(it->name);
-      query_.prototype.append(column_definition{(*it).name});
+      query_.prototype.emplace_back((*it).name);
     }
   }
 
@@ -54,7 +54,7 @@ void query_compiler::visit(query_select_part &select_part)
 void query_compiler::visit(query_from_part &from_part)
 {
   query_.table = from_part.table();
-  if (dialect_.default_schema_name().empty()) {
+  if (!dialect_.default_schema_name().empty()) {
     query_.sql += " " + dialect_.token_at(dialect::token_t::FROM) +
                   " " + dialect_.prepare_identifier(from_part.table().name) +
                   (from_part.table().alias.empty() ? "" : " AS " +
@@ -70,9 +70,17 @@ void query_compiler::visit(query_from_part &from_part)
 
 void query_compiler::visit(query_join_part &join_part)
 {
+  if (dialect_.default_schema_name().empty()) {
     query_.sql += " " + dialect_.token_at(dialect::token_t::JOIN) +
                   " " + dialect_.prepare_identifier(join_part.table().name) +
                   (join_part.table().alias.empty() ? "" : " AS " + dialect_.prepare_identifier(join_part.table().alias));
+  } else {
+    query_.sql += " " + dialect_.token_at(dialect::token_t::JOIN) +
+                  " " + dialect_.prepare_identifier(dialect_.default_schema_name()) +
+                  "." + dialect_.prepare_identifier(join_part.table().name) +
+                  (join_part.table().alias.empty() ? "" : " AS " + dialect_.prepare_identifier(join_part.table().alias));
+
+  }
 }
 
 void query_compiler::visit(query_on_part &on_part)

src/sql/query_intermediates.cpp

@@ -8,157 +8,157 @@ basic_query_intermediate::basic_query_intermediate(connection &db, const sql::sc
 : connection_(db)
 , schema_(schema) {}
 
-query_result<record> query_select_finish::fetch_all()
+query_result<record> query_select::fetch_all()
 {
   query_compiler compiler(connection_.dialect());
-  return connection_.fetch(compiler.compile(&data_));
+  return connection_.fetch(compiler.compile(data_.get()));
 }
 
-record query_select_finish::fetch_one()
+std::optional<record> query_select::fetch_one()
 {
   query_compiler compiler(connection_.dialect());
-  return *connection_.fetch(compiler.compile(&data_)).begin().get();
+  auto result = connection_.fetch(compiler.compile(data_.get()));
+  auto first = result.begin();
+  if (first == result.end()) {
+    return std::nullopt;
   }
 
-query_context query_select_finish::build() const
+  return *first.get();
+}
+
+query_context query_select::build() const
 {
   query_compiler compiler(connection_.dialect());
-  return compiler.compile(&data_);
+  return compiler.compile(data_.get());
 }
 
-std::unique_ptr<query_result_impl> query_select_finish::fetch()
+std::unique_ptr<query_result_impl> query_select::fetch()
 {
   query_compiler compiler(connection_.dialect());
-  return connection_.fetch(compiler.compile(&data_).sql);
+  return connection_.fetch(compiler.compile(data_.get()).sql);
 }
 
-statement query_select_finish::prepare()
+statement query_select::prepare()
 {
   query_compiler compiler(connection_.dialect());
-  return connection_.prepare(compiler.compile(&data_));
+  return connection_.prepare(compiler.compile(data_.get()));
 }
 
-query_intermediate::query_intermediate(connection &db, const sql::schema &schema, query_data &data)
+query_intermediate::query_intermediate(connection &db, const sql::schema &schema, const std::shared_ptr<query_data> &data)
 : basic_query_intermediate(db, schema), data_(data) {}
 
 query_offset_intermediate query_limit_intermediate::offset(size_t offset)
 {
-  data_.parts.push_back(std::make_unique<query_offset_part>(offset));
+  data_->parts.push_back(std::make_unique<query_offset_part>(offset));
   return {connection_, schema_, data_};
 }
 
 query_limit_intermediate query_offset_intermediate::limit(size_t limit)
 {
-  data_.parts.push_back(std::make_unique<query_limit_part>(limit));
+  data_->parts.push_back(std::make_unique<query_limit_part>(limit));
   return {connection_, schema_, data_};
 }
 
 query_limit_intermediate query_order_direction_intermediate::limit(size_t limit)
 {
-  data_.parts.push_back(std::make_unique<query_limit_part>(limit));
+  data_->parts.push_back(std::make_unique<query_limit_part>(limit));
   return {connection_, schema_, data_};
 }
 
 query_order_by_intermediate query_group_by_intermediate::order_by(const column &col)
 {
-  data_.parts.push_back(std::make_unique<query_order_by_part>(col));
+  data_->parts.push_back(std::make_unique<query_order_by_part>(col));
   return {connection_, schema_, data_};
 }
 
 query_order_direction_intermediate query_order_by_intermediate::asc()
 {
-  data_.parts.push_back(std::make_unique<query_order_by_asc_part>());
+  data_->parts.push_back(std::make_unique<query_order_by_asc_part>());
   return {connection_, schema_, data_};
 }
 
 query_order_direction_intermediate query_order_by_intermediate::desc()
 {
-  data_.parts.push_back(std::make_unique<query_order_by_desc_part>());
+  data_->parts.push_back(std::make_unique<query_order_by_desc_part>());
   return {connection_, schema_, data_};
 }
 
 query_where_intermediate query_from_intermediate::where_clause(std::unique_ptr<basic_condition> &&cond)
 {
-  data_.parts.push_back(std::make_unique<query_where_part>(std::move(cond)));
+  if (cond) {
+    data_->parts.push_back(std::make_unique<query_where_part>(std::move(cond)));
+  }
   return {connection_, schema_, data_};
 }
 
 query_group_by_intermediate query_from_intermediate::group_by(const column &col)
 {
-  data_.parts.push_back(std::make_unique<query_group_by_part>(col));
+  data_->parts.push_back(std::make_unique<query_group_by_part>(col));
   return {connection_, schema_, data_};
 }
 
 query_order_by_intermediate query_from_intermediate::order_by(const column &col)
 {
-  data_.parts.push_back(std::make_unique<query_order_by_part>(col));
+  data_->parts.push_back(std::make_unique<query_order_by_part>(col));
   return {connection_, schema_, data_};
 }
 
 query_group_by_intermediate query_where_intermediate::group_by(const column &col)
 {
-  data_.parts.push_back(std::make_unique<query_group_by_part>(col));
+  data_->parts.push_back(std::make_unique<query_group_by_part>(col));
   return {connection_, schema_, data_};
 }
 
 query_order_by_intermediate query_where_intermediate::order_by(const column &col)
 {
-  data_.parts.push_back(std::make_unique<query_order_by_part>(col));
+  data_->parts.push_back(std::make_unique<query_order_by_part>(col));
-  return {connection_, schema_, data_};
-}
-
-query_join_intermediate query_on_intermediate::join_left(const table &t)
-{
-  data_.parts.push_back(std::make_unique<query_join_part>(t));
-  return {connection_, schema_, data_};
-}
-
-query_where_intermediate query_on_intermediate::where_clause(std::unique_ptr<basic_condition> &&cond)
-{
-  data_.parts.push_back(std::make_unique<query_where_part>(std::move(cond)));
-  return {connection_, schema_, data_};
-}
-
-query_group_by_intermediate query_on_intermediate::group_by(const column &col)
-{
-  data_.parts.push_back(std::make_unique<query_group_by_part>(col));
-  return {connection_, schema_, data_};
-}
-
-query_order_by_intermediate query_on_intermediate::order_by(const column &col)
-{
-  data_.parts.push_back(std::make_unique<query_order_by_part>(col));
   return {connection_, schema_, data_};
 }
 
 query_on_intermediate query_join_intermediate::on_clause(std::unique_ptr<basic_condition> &&cond)
 {
-  data_.parts.push_back(std::make_unique<query_on_part>(std::move(cond)));
+  data_->parts.push_back(std::make_unique<query_on_part>(std::move(cond)));
   return {connection_, schema_, data_};
 }
 
 query_join_intermediate query_from_intermediate::join_left(const table &t)
 {
-  data_.parts.push_back(std::make_unique<query_join_part>(t));
+  data_->parts.push_back(std::make_unique<query_join_part>(t));
+  return {connection_, schema_, data_};
+}
+
+query_from_intermediate query_from_intermediate::join_left(join_data &data)
+{
+  data_->parts.push_back(std::make_unique<query_join_part>(data.join_table));
+  data_->parts.push_back(std::make_unique<query_on_part>(std::move(data.condition)));
+  return {connection_, schema_, data_};
+}
+
+query_from_intermediate query_from_intermediate::join_left(std::vector<join_data> &data_vector)
+{
+  for (auto &data : data_vector) {
+    data_->parts.push_back(std::make_unique<query_join_part>(data.join_table));
+    data_->parts.push_back(std::make_unique<query_on_part>(std::move(data.condition)));
+  }
   return {connection_, schema_, data_};
 }
 
 query_select_intermediate::query_select_intermediate(connection &db, const sql::schema &schema, const std::vector<column>& columns)
 : query_start_intermediate(db, schema)
 {
-  data_.parts.push_back(std::make_unique<query_select_part>(columns));
+  data_->parts.push_back(std::make_unique<query_select_part>(columns));
 }
 
 query_from_intermediate query_select_intermediate::from(const table& t)
 {
-  data_.parts.push_back(std::make_unique<query_from_part>(t));
+  data_->parts.push_back(std::make_unique<query_from_part>(t));
   return {connection_, schema_, data_};
 }
 
 query_insert_intermediate::query_insert_intermediate(connection &db, const sql::schema &schema)
 : query_start_intermediate(db, schema)
 {
-  data_.parts.push_back(std::make_unique<query_insert_part>());
+  data_->parts.push_back(std::make_unique<query_insert_part>());
 }
 
 query_into_intermediate query_insert_intermediate::into(const sql::table &table, std::initializer_list<column> column_names)
@@ -168,83 +168,89 @@ query_into_intermediate query_insert_intermediate::into(const sql::table &table,
 
 query_into_intermediate query_insert_intermediate::into(const table &table, std::vector<column> &&column_names)
 {
-  data_.parts.push_back(std::make_unique<query_into_part>(table, column_names));
+  data_->parts.push_back(std::make_unique<query_into_part>(table, column_names));
   return {connection_, schema_, data_};
 }
 
-size_t query_execute_finish::execute()
+query_into_intermediate query_insert_intermediate::into(const table &table)
 {
-  query_compiler compiler(connection_.dialect());
+  data_->parts.push_back(std::make_unique<query_into_part>(table, table.columns));
-  return connection_.execute(compiler.compile(&data_).sql);
+  return {connection_, schema_, data_};
 }
 
-statement query_execute_finish::prepare()
+size_t query_execute::execute()
 {
   query_compiler compiler(connection_.dialect());
-  return connection_.prepare(compiler.compile(&data_));
+  return connection_.execute(compiler.compile(data_.get()).sql);
 }
 
-query_context query_execute_finish::build() const
+statement query_execute::prepare()
 {
   query_compiler compiler(connection_.dialect());
-  return compiler.compile(&data_);
+  return connection_.prepare(compiler.compile(data_.get()));
 }
 
-query_execute_finish query_into_intermediate::values(std::initializer_list<any_type> values)
+query_context query_execute::build() const
+{
+  query_compiler compiler(connection_.dialect());
+  return compiler.compile(data_.get());
+}
+
+query_execute query_into_intermediate::values(std::initializer_list<any_type> values)
 {
   return this->values(std::vector<any_type>(values));
 }
 
-query_execute_finish query_into_intermediate::values(std::vector<any_type> &&values)
+query_execute query_into_intermediate::values(std::vector<any_type> &&values)
 {
-  data_.parts.push_back(std::make_unique<query_values_part>(std::move(values)));
+  data_->parts.push_back(std::make_unique<query_values_part>(std::move(values)));
   return {connection_, schema_, data_};
 }
 
 query_create_intermediate::query_create_intermediate(connection &db, const sql::schema &schema)
 : query_start_intermediate(db, schema) {
-  data_.parts.push_back(std::make_unique<query_create_part>());
+  data_->parts.push_back(std::make_unique<query_create_part>());
 }
 
-query_execute_finish query_create_intermediate::table(const sql::table &table, std::initializer_list<column_definition> columns)
+query_execute query_create_intermediate::table(const sql::table &table, std::initializer_list<column_definition> columns)
 {
   return this->table(table, std::vector<column_definition>{columns});
 }
 
-query_execute_finish query_create_intermediate::table(const sql::table &table, const std::vector<column_definition> &columns)
+query_execute query_create_intermediate::table(const sql::table &table, const std::vector<column_definition> &columns)
 {
-  data_.parts.push_back(std::make_unique<query_create_table_part>(table, columns));
+  data_->parts.push_back(std::make_unique<query_create_table_part>(table, columns));
   return {connection_, schema_, data_};
 }
 
 query_drop_intermediate::query_drop_intermediate(connection &db, const sql::schema &schema)
 : query_start_intermediate(db, schema)
 {
-  data_.parts.push_back(std::make_unique<query_drop_part>());
+  data_->parts.push_back(std::make_unique<query_drop_part>());
 }
 
-query_execute_finish query_drop_intermediate::table(const sql::table &table)
+query_execute query_drop_intermediate::table(const sql::table &table)
 {
-  data_.parts.push_back(std::make_unique<query_drop_table_part>(table));
+  data_->parts.push_back(std::make_unique<query_drop_table_part>(table));
   return {connection_, schema_, data_};
 }
 
 query_order_by_intermediate query_execute_where_intermediate::order_by(const column &col)
 {
-  data_.parts.push_back(std::make_unique<query_order_by_part>(col));
+  data_->parts.push_back(std::make_unique<query_order_by_part>(col));
   return {connection_, schema_, data_};
 }
 
 query_execute_where_intermediate query_set_intermediate::where_clause(std::unique_ptr<basic_condition> &&cond)
 {
-  data_.parts.push_back(std::make_unique<query_where_part>(std::move(cond)));
+  data_->parts.push_back(std::make_unique<query_where_part>(std::move(cond)));
   return {connection_, schema_, data_};
 }
 
 query_update_intermediate::query_update_intermediate(connection &db, const sql::schema &schema, const sql::table& table)
 : query_start_intermediate(db, schema)
 {
-  data_.parts.push_back(std::make_unique<query_update_part>(table));
+  data_->parts.push_back(std::make_unique<query_update_part>(table));
 }
 
 query_set_intermediate query_update_intermediate::set(std::initializer_list<key_value_pair> columns)
@@ -254,26 +260,26 @@ query_set_intermediate query_update_intermediate::set(std::initializer_list<key_
 
 query_set_intermediate query_update_intermediate::set(std::vector<key_value_pair> &&columns)
 {
-  data_.parts.push_back(std::make_unique<query_set_part>(std::move(columns)));
+  data_->parts.push_back(std::make_unique<query_set_part>(std::move(columns)));
   return {connection_, schema_, data_};
 
 }
 
 query_execute_where_intermediate query_delete_from_intermediate::where_clause(std::unique_ptr<basic_condition> &&cond)
 {
-  data_.parts.push_back(std::make_unique<query_where_part>(std::move(cond)));
+  data_->parts.push_back(std::make_unique<query_where_part>(std::move(cond)));
   return {connection_, schema_, data_};
 }
 
 query_delete_intermediate::query_delete_intermediate(connection &db, const sql::schema &schema)
 : query_start_intermediate(db, schema)
 {
-  data_.parts.push_back(std::make_unique<query_delete_part>());
+  data_->parts.push_back(std::make_unique<query_delete_part>());
 }
 
 query_delete_from_intermediate query_delete_intermediate::from(const sql::table &table)
 {
-  data_.parts.push_back(std::make_unique<query_delete_from_part>(table));
+  data_->parts.push_back(std::make_unique<query_delete_from_part>(table));
   return {connection_, schema_, data_};
 }
 

src/sql/query_result.cpp

@@ -1,11 +1,17 @@
 #include "matador/sql/query_result.hpp"
 
+#include "matador/sql/record.hpp"
+
 namespace matador::sql::detail {
 
 template<>
-record *create_prototype<record>(const record &prototype)
+record *create_prototype<record>(const std::vector<column_definition> &prototype)
 {
-  return new record{prototype};
+  auto result = std::make_unique<record>();
+  for (const auto &col: prototype) {
+    result->append({col.name(), col.type(), col.attributes().size(), col.index()});
+  }
+  return result.release();
 }
 
 }

src/sql/query_result_impl.cpp

@@ -1,5 +1,6 @@
 #include "matador/sql/query_result_impl.hpp"
 #include "matador/sql/query_result_reader.hpp"
+#include "matador/sql/value.hpp"
 
 namespace matador::sql {
 
@@ -11,7 +12,7 @@ void detail::pk_reader::on_primary_key(const char *id, std::string &value, size_
   data_type_traits<std::string>::read_value(reader_, id, column_index_++, value, size);
 }
 
-query_result_impl::query_result_impl(std::unique_ptr<query_result_reader> &&reader, record prototype)
+query_result_impl::query_result_impl(std::unique_ptr<query_result_reader> &&reader, std::vector<column_definition> prototype)
 : prototype_(std::move(prototype))
 , reader_(std::move(reader))
 , pk_reader_(*reader_)
@@ -39,12 +40,12 @@ void query_result_impl::on_attribute(const char *id, std::string &value, const u
 }
 
 void
-query_result_impl::on_attribute(const char *id, any_type &value, data_type_t type, const utils::field_attributes &attr)
+query_result_impl::on_attribute(const char *id, value &val, const utils::field_attributes &attr)
 {
-  reader_->read_value(id, column_index_++, value, type, attr.size());
+  reader_->read_value(id, column_index_++, val, attr.size());
 }
 
-const record& query_result_impl::prototype() const
+const std::vector<column_definition>& query_result_impl::prototype() const
 {
   return prototype_;
 }

src/sql/query_result_reader.cpp

@@ -1,5 +1,6 @@
 #include "matador/sql/query_result_reader.hpp"
 #include "matador/sql/to_value.hpp"
+#include "matador/sql/value.hpp"
 
 namespace matador::sql {
 
@@ -104,82 +105,82 @@ void query_result_reader::read_value(const char *id, size_t index, utils::blob &
 }
 
 template < typename Type >
-void convert(const char *valstr, sql::any_type &value)
+void convert(const char *valstr, value &val)
 {
-  Type val{};
+  Type local_val{};
-  sql::to_value(val, valstr);
+  sql::to_value(local_val, valstr);
-  value = val;
+  val = local_val;
 }
 
-void query_result_reader::read_value(const char *id, size_t index, any_type &value, data_type_t type, size_t size)
+void query_result_reader::read_value(const char *id, size_t index, value &val, size_t size)
 {
-  switch (type) {
+  switch (val.type()) {
     case sql::data_type_t::type_char:
-      convert<char>(column(index), value);
+      convert<char>(column(index), val);
       break;
     case sql::data_type_t::type_short:
-      convert<short>(column(index), value);
+      convert<short>(column(index), val);
       break;
     case sql::data_type_t::type_int:
-      convert<int>(column(index), value);
+      convert<int>(column(index), val);
       break;
     case sql::data_type_t::type_long:
-      convert<long>(column(index), value);
+      convert<long>(column(index), val);
       break;
     case sql::data_type_t::type_long_long:
-      convert<long long>(column(index), value);
+      convert<long long>(column(index), val);
       break;
     case sql::data_type_t::type_unsigned_char:
-      convert<unsigned char>(column(index), value);
+      convert<unsigned char>(column(index), val);
       break;
     case sql::data_type_t::type_unsigned_short:
-      convert<unsigned short>(column(index), value);
+      convert<unsigned short>(column(index), val);
       break;
     case sql::data_type_t::type_unsigned_int:
-      convert<unsigned int>(column(index), value);
+      convert<unsigned int>(column(index), val);
       break;
     case sql::data_type_t::type_unsigned_long:
-      convert<unsigned long>(column(index), value);
+      convert<unsigned long>(column(index), val);
       break;
     case sql::data_type_t::type_unsigned_long_long:
-      convert<unsigned long long>(column(index), value);
+      convert<unsigned long long>(column(index), val);
       break;
     case sql::data_type_t::type_float:
-      convert<float>(column(index), value);
+      convert<float>(column(index), val);
       break;
     case sql::data_type_t::type_double:
-      convert<double>(column(index), value);
+      convert<double>(column(index), val);
       break;
     case sql::data_type_t::type_bool: {
-      int val{};
+      int local_val{};
-      sql::to_value(val, column(index));
+      sql::to_value(local_val, column(index));
-      value = val > 0;
+      val = local_val > 0;
       break;
     }
     case sql::data_type_t::type_text:
     case sql::data_type_t::type_varchar: {
-      value = std::string{column(index)};
+      val = std::string{column(index)};
       break;
     }
     case sql::data_type_t::type_char_pointer: {
-      value = column(index);
+      val = column(index);
       break;
     }
     case sql::data_type_t::type_time:
     case sql::data_type_t::type_date: {
-      value = std::string{column(index)};
+      val = std::string{column(index)};
       break;
     }
     case sql::data_type_t::type_null: {
-      value = nullptr_t{};
+      val = nullptr_t{};
       break;
     }
     case sql::data_type_t::type_blob: {
-      value = utils::blob{};
+      val = utils::blob{};
       break;
     }
     case sql::data_type_t::type_unknown: {
-      value = std::string(column(index));
+      val = std::string(column(index));
       break;
     }
   }

src/sql/record.cpp

@@ -6,24 +6,28 @@
 
 namespace matador::sql {
 
-record::record(std::initializer_list<column_definition> columns)
+record::record(std::initializer_list<field> columns)
-: columns_(columns)
 {
-  init();
+  for (auto &&col :columns) {
+    const auto it = fields_by_name_.emplace(col.name(), field_index_pair {col, fields_.size()});
+    fields_.push_back(std::ref(it.first->second.first));
+  }
 }
 
-record::record(const std::vector<column_definition> &columns)
+record::record(const std::vector<field> &columns)
-: columns_(columns)
 {
-  init();
+  for (auto &&col :columns) {
+    const auto it = fields_by_name_.emplace(col.name(), field_index_pair {col, fields_.size()});
+    fields_.push_back(std::ref(it.first->second.first));
+  }
 }
 
 record::record(const record &x)
-: columns_(x.columns_)
+: fields_by_name_(x.fields_by_name_)
-, pk_index_(x.pk_index_)
+//, pk_index_(x.pk_index_)
 {
-  for (auto& col : columns_) {
+  for (auto& col : fields_by_name_) {
-    add_to_map(col, col.index());
+    fields_.push_back(std::ref(col.second.first));
   }
 }
 
@@ -33,135 +37,130 @@ record &record::operator=(const record &x)
     return *this;
   }
 
-  columns_ = x.columns_;
+  fields_by_name_ = x.fields_by_name_;
-  columns_by_name_.clear();
+  fields_.clear();
-  pk_index_ = x.pk_index_;
+//  pk_index_ = x.pk_index_;
-  for (auto& col : columns_) {
+  for (auto& col : fields_by_name_) {
-    add_to_map(col, col.index());
+    fields_.push_back(std::ref(col.second.first));
   }
   return *this;
 }
 
-const std::vector<column_definition> &record::columns() const
+const std::vector<record::field_ref> &record::columns() const
 {
-  return columns_;
+  return fields_;
 }
 
-bool record::has_primary_key() const
+//bool record::has_primary_key() const
-{
-  return pk_index_ > -1;
-}
-
-const column_definition &record::primary_key() const
-{
-  if (!has_primary_key()) {
-    throw std::logic_error("record has no primary key");
-  }
-
-  return columns_[pk_index_];
-}
-
-const column_definition &record::at(const column &col) const
-{
-  auto ref = columns_by_name_.at(col.name).first;
-  return columns_by_name_.at(col.name).first;
-}
-
-//const column_definition &record::at(const std::string &name) const
 //{
-//  auto ref = columns_by_name_.at(name).first;
+//  return pk_index_ > -1;
-//  return columns_by_name_.at(name).first;
+//}
+//
+//std::optional<field> record::primary_key() const
+//{
+//  if (!has_primary_key()) {
+//    return std::nullopt;
+//  }
+//
+//  return columns_[pk_index_];
 //}
 
-const column_definition &record::at(size_t index) const
+const field &record::at(const column &col) const
 {
-  return columns_.at(index);
+  const auto &res = fields_by_name_.at(col.name);
+  const auto &f = res.first;
+  return f;
+}
+
+const field &record::at(size_t index) const
+{
+  return fields_.at(index);
 }
 
 record::iterator record::find(const std::string &column_name)
 {
-  auto it = columns_by_name_.find(column_name);
+  auto it = fields_by_name_.find(column_name);
-  return it != columns_by_name_.end() ? columns_.begin() + it->second.second : columns_.end();
+  return it != fields_by_name_.end() ? fields_.begin() + it->second.second : fields_.end();
 }
 
 record::const_iterator record::find(const std::string &column_name) const {
-  auto it = columns_by_name_.find(column_name);
+  auto it = fields_by_name_.find(column_name);
-  return it != columns_by_name_.end() ? columns_.begin() + it->second.second : columns_.end();
+  return it != fields_by_name_.end() ? fields_.begin() + it->second.second : fields_.end();
 }
 
-void record::append(column_definition col)
+void record::append(const field &col)
 {
-  auto &ref = columns_.emplace_back(std::move(col));
+  const auto it = fields_by_name_.emplace(col.name(), field_index_pair {col, fields_.size()});
-  add_to_map(ref, columns_.size()-1);
+  fields_.push_back(std::ref(it.first->second.first));
 }
 
 record::iterator record::begin()
 {
-  return columns_.begin();
+  return fields_.begin();
 }
 
 record::const_iterator record::begin() const
 {
-  return columns_.begin();
+  return fields_.begin();
 }
 
 record::const_iterator record::cbegin() const
 {
-  return columns_.cbegin();
+  return fields_.cbegin();
 }
 
 record::iterator record::end()
 {
-  return columns_.end();
+  return fields_.end();
 }
 
 record::const_iterator record::end() const
 {
-  return columns_.end();
+  return fields_.end();
 }
 
 record::const_iterator record::cend() const
 {
-  return columns_.cend();
+  return fields_.cend();
 }
 
 size_t record::size() const
 {
-  return columns_.size();
+  return fields_.size();
 }
 
 bool record::empty() const
 {
-  return columns_.empty();
+  return fields_.empty();
 }
 
 void record::clear()
 {
-  columns_.clear();
+  fields_.clear();
-  columns_by_name_.clear();
+  fields_by_name_.clear();
 }
 
-bool record::unknown() const
+//bool record::unknown() const
-{
+//{
-  return std::all_of(std::begin(columns_), std::end(columns_), [](const auto &col) {
+//  return std::all_of(std::begin(columns_), std::end(columns_), [](const auto &col) {
-    return col.type() == data_type_t::type_unknown;
+//    return col.type() == data_type_t::type_unknown;
-  });
+//  });
-}
+//}
 
 void record::init()
 {
   size_t index{0};
-  for(auto &col : columns_) {
+  for(auto &col : fields_) {
     add_to_map(col, index++);
   }
 }
 
-void record::add_to_map(column_definition &col, size_t index)
+void record::add_to_map(field &col, size_t index)
 {
-  columns_by_name_.emplace(col.name(), column_index_pair {std::ref(col), index});
+  fields_by_name_.emplace(col.name(), field_index_pair {std::ref(col), index});
-  if (utils::is_constraint_set(col.attributes().options(), utils::constraints::PRIMARY_KEY)) {
+//  if (utils::is_constraint_set(col.attributes().options(), utils::constraints::PRIMARY_KEY)) {
-    pk_index_ = static_cast<int>(index);
+//    pk_index_ = static_cast<int>(index);
-  }
+//  }
 }
 
 }

src/sql/schema.cpp

@@ -5,19 +5,16 @@
 
 namespace matador::sql {
 
-void table_info::create(connection &conn, schema &scm) const
-{
-  conn.query(scm).create().table(name, prototype.columns()).execute();
-}
-
-void table_info::drop(connection &conn, schema &scm) const
-{
-  conn.query(scm).drop().table(name).execute();
-}
-
 schema::schema(std::string name)
 : name_(std::move(name)) {}
 
+void schema::create(connection &c) {
+    for (const auto &ti : repository_) {
+        // ti.second.prototype
+
+    }
+}
+
 std::string schema::name() const
 {
   return name_;
@@ -25,7 +22,10 @@ std::string schema::name() const
 
 const table_info& schema::attach(const std::type_index ti, const table_info& table)
 {
-  return repository_.try_emplace(ti, table).first->second;
+
+  auto &ref = repository_.try_emplace(ti, table).first->second;
+  repository_by_name_.try_emplace(ref.name, std::ref(ref));
+  return ref;
 }
 
 std::optional<table_info> schema::info(std::type_index ti) const
@@ -37,6 +37,15 @@ std::optional<table_info> schema::info(std::type_index ti) const
   return it->second;
 }
 
+std::optional<table_info> schema::info(const std::string &name) const
+{
+  const auto it = repository_by_name_.find(name);
+  if (it == repository_by_name_.end()) {
+    return std::nullopt;
+  }
+  return it->second;
+}
+
 std::pair<std::string, std::string> schema::reference(const std::type_index &ti) const
 {
   const auto it = repository_.find(ti);
@@ -44,7 +53,7 @@ std::pair<std::string, std::string> schema::reference(const std::type_index &ti)
     if (!it->second.prototype.has_primary_key()) {
       throw std::logic_error("table doesn't has primary key");
     }
-    return { it->second.name, it->second.prototype.primary_key().name() };
+    return { it->second.name, it->second.prototype.primary_key().value().name() };
   }
 
   return {};

src/sql/session.cpp

@@ -15,7 +15,7 @@ void session::create_schema()
 {
   auto c = pool_.acquire();
   for (const auto &t : *schema_) {
-    t.second.create(*c, *schema_);
+    c->query(*schema_).create().table(t.second.name, t.second.prototype.columns()).execute();
   }
 }
 
@@ -71,7 +71,7 @@ statement session::prepare(query_context q) const
   return c->prepare(std::move(q));
 }
 
-record session::describe_table(const std::string &table_name) const
+std::vector<sql::column_definition> session::describe_table(const std::string &table_name) const
 {
   auto c = pool_.acquire();
   if (!c.valid()) {
@@ -89,11 +89,6 @@ bool session::table_exists(const std::string &table_name) const
   return c->exists(dialect_.default_schema_name(), table_name);
 }
 
-const schema& session::tables() const
-{
-  return *schema_;
-}
-
 const class dialect &session::dialect() const
 {
   return dialect_;
@@ -108,4 +103,15 @@ std::unique_ptr<query_result_impl> session::fetch(const std::string &sql) const
   return c->fetch(sql);
 }
 
+query_select session::build_select_query(connection_ptr<connection> &conn, entity_query_data &&data) const
+{
+  return conn->query(*schema_)
+    .select(data.columns)
+    .from(data.root_table_name)
+    .join_left(data.joins)
+    .where(std::move(data.where_clause))
+    .order_by({data.root_table_name, data.pk_column_})
+    .asc();
+}
+
 }

src/sql/table_definition.cpp

@@ -0,0 +1,148 @@
+#include "matador/sql/table_definition.hpp"
+
+namespace matador::sql {
+table_definition::table_definition(std::initializer_list<column_definition> columns)
+: columns_(columns)
+{
+  init();
+}
+
+table_definition::table_definition(const std::vector<column_definition> &columns)
+: columns_(columns)
+{
+  init();
+}
+
+table_definition::table_definition(const table_definition &x)
+: columns_(x.columns_)
+, pk_index_(x.pk_index_)
+{
+  for (auto& col : columns_) {
+    add_to_map(col, col.index());
+  }
+}
+
+table_definition &table_definition::operator=(const table_definition &x)
+{
+  if (&x == this) {
+    return *this;
+  }
+
+  columns_ = x.columns_;
+  columns_by_name_.clear();
+  pk_index_ = x.pk_index_;
+  for (auto& col : columns_) {
+    add_to_map(col, col.index());
+  }
+  return *this;
+}
+
+bool table_definition::has_primary_key() const
+{
+    return pk_index_ > -1;
+}
+
+std::optional<column_definition> table_definition::primary_key() const
+{
+  if (!has_primary_key()) {
+    return std::nullopt;
+  }
+
+  return columns_[pk_index_];
+}
+
+void table_definition::append(column_definition col)
+{
+  auto &ref = columns_.emplace_back(std::move(col));
+  add_to_map(ref, columns_.size()-1);
+}
+
+const std::vector<column_definition> &table_definition::columns() const
+{
+  return columns_;
+}
+
+const column_definition &table_definition::at(const column &col) const
+{
+  return columns_by_name_.at(col.name).first;
+}
+
+const column_definition &table_definition::at(size_t index) const
+{
+  return columns_.at(index);
+}
+
+table_definition::iterator table_definition::find(const std::string &column_name)
+{
+  auto it = columns_by_name_.find(column_name);
+  return it != columns_by_name_.end() ? columns_.begin() + it->second.second : columns_.end();
+}
+
+table_definition::const_iterator table_definition::find(const std::string &column_name) const {
+  auto it = columns_by_name_.find(column_name);
+  return it != columns_by_name_.end() ? columns_.begin() + it->second.second : columns_.end();
+}
+
+table_definition::iterator table_definition::begin()
+{
+  return columns_.begin();
+}
+
+table_definition::const_iterator table_definition::begin() const
+{
+  return columns_.begin();
+}
+
+table_definition::const_iterator table_definition::cbegin() const
+{
+  return columns_.cbegin();
+}
+
+table_definition::iterator table_definition::end()
+{
+  return columns_.end();
+}
+
+table_definition::const_iterator table_definition::end() const
+{
+  return columns_.end();
+}
+
+table_definition::const_iterator table_definition::cend() const
+{
+  return columns_.cend();
+}
+
+size_t table_definition::size() const
+{
+  return columns_.size();
+}
+
+bool table_definition::empty() const
+{
+  return columns_.empty();
+}
+
+void table_definition::clear()
+{
+  columns_.clear();
+  columns_by_name_.clear();
+}
+
+void table_definition::init()
+{
+  size_t index{0};
+  for(auto &col : columns_) {
+    add_to_map(col, index++);
+  }
+}
+
+void table_definition::add_to_map(column_definition &col, size_t index)
+{
+  columns_by_name_.emplace(col.name(), column_index_pair {std::ref(col), index});
+  if (utils::is_constraint_set(col.attributes().options(), utils::constraints::PRIMARY_KEY)) {
+    pk_index_ = static_cast<int>(index);
+  }
+}
+
+}

src/sql/value.cpp

@@ -0,0 +1,101 @@
+#include "matador/sql/value.hpp"
+
+#include <cstring>
+
+namespace matador::sql {
+namespace detail {
+
+size_t determine_size(const std::string &val)
+{
+  return val.size();
+}
+
+size_t determine_size(const char *val)
+{
+  return strlen(val);
+}
+
+size_t determine_size(const utils::blob &val)
+{
+  return val.size();
+}
+
+}
+value::value(data_type_t data_type, size_t size)
+: size_(size)
+, type_(data_type) {}
+
+value::value(value &&x) noexcept
+  : value_(std::move(x.value_))
+  , type_(x.type_)
+{
+  x.value_ = nullptr;
+  x.type_ = data_type_t::type_unknown;
+}
+
+value &value::operator=(value &&x) noexcept
+{
+  value_ = std::move(x.value_);
+  type_ = x.type_;
+  x.value_ = nullptr;
+  x.type_ = data_type_t::type_unknown;
+
+  return *this;
+}
+
+std::string value::str() const
+{
+  return as<std::string>().value();
+}
+
+size_t value::size() const
+{
+  return size_;
+}
+
+data_type_t value::type() const
+{
+  return type_;
+}
+
+bool value::is_integer() const
+{
+  return type_ >= data_type_t::type_char && type_ <= data_type_t::type_unsigned_long_long;
+}
+
+bool value::is_floating_point() const
+{
+  return type_ == data_type_t::type_float || type_ == data_type_t::type_double;
+}
+
+bool value::is_bool() const
+{
+  return type_ == data_type_t::type_bool;
+}
+
+bool value::is_string() const
+{
+  return type_ == data_type_t::type_text;
+}
+
+bool value::is_varchar() const
+{
+  return type_ == data_type_t::type_varchar || type_ == data_type_t::type_char_pointer;
+}
+
+bool value::is_blob() const
+{
+  return type_ == data_type_t::type_blob;
+}
+
+bool value::is_null() const
+{
+  return type_ == data_type_t::type_null;
+}
+
+bool value::is_unknown() const
+{
+  return type_ == data_type_t::type_unknown;
+}
+
+}

test/BackendProviderTest.cpp

@@ -9,6 +9,8 @@ using namespace matador::sql;
 
 TEST_CASE("Load backend", "[backend provider]") {
   auto path = matador::utils::os::getenv("MATADOR_BACKENDS_PATH");
+  REQUIRE(!path.empty());
+
   if (path.back() != '\\') {
     path.push_back('\\');
   }
@@ -16,8 +18,8 @@ TEST_CASE("Load backend", "[backend provider]") {
   REQUIRE(!path.empty());
 
   connection_info ci{};
-  const auto &d = backend_provider::instance().connection_dialect("sqlite");
+  const auto &d = backend_provider::instance().connection_dialect("noop");
-  auto *connection = backend_provider::instance().create_connection("sqlite", ci);
+  auto *connection = backend_provider::instance().create_connection("noop", ci);
   REQUIRE(connection != nullptr);
-  backend_provider::instance().destroy_connection("sqlite", connection);
+  backend_provider::instance().destroy_connection("noop", connection);
 }