added timestamp code, support columns for group by and order by and tested load has-many eager code

include/matador/utils/access.hpp

@@ -2,16 +2,12 @@
 #define OOS_ACCESS_HPP
 
 #include <cstdint>
-#include <string>
 #include <optional>
 
 namespace matador {
 
 enum class cascade_type;
 
-template < class Type, template < class ... > class ContainerType >
-class container;
-
 namespace utils {
 class field_attributes;
 class foreign_attributes;

include/matador/utils/identifier.hpp

@@ -194,6 +194,7 @@ public:
   [[nodiscard]] bool is_varchar() const;
   [[nodiscard]] bool is_date() const;
   [[nodiscard]] bool is_time() const;
+  [[nodiscard]] bool is_timestamp() const;
   [[nodiscard]] bool is_blob() const;
   [[nodiscard]] bool is_null() const;
 

include/matador/utils/value.hpp

@@ -18,15 +18,19 @@ size_t determine_size(const blob_type_t &val);
 
 }
 
-class value
-{
+class value {
 public:
   value() = default;
-  template<typename Type>
+  template<typename Type, std::enable_if_t<!std::is_enum_v<Type>>* = nullptr>
   explicit value(Type value, size_t size = 0)
   : value_(value)
   , size_(size)
   , type_(data_type_traits<Type>::type(size)) {}
+  template<typename Type, std::enable_if_t<std::is_enum_v<Type>>* = nullptr>
+  explicit value(Type value, size_t size = 0)
+  : value_(static_cast<int>(value))
+  , size_(size)
+  , type_(data_type_traits<Type>::type(size)) {}
   explicit value(basic_type data_type, size_t size = 0);
   value(const value &x) = default;
   value& operator=(const value &x) = default;
@@ -74,11 +78,12 @@ public:
   [[nodiscard]] bool is_varchar() const;
   [[nodiscard]] bool is_date() const;
   [[nodiscard]] bool is_time() const;
+  [[nodiscard]] bool is_timestamp() const;
   [[nodiscard]] bool is_blob() const;
   [[nodiscard]] bool is_null() const;
 
 private:
-  utils::database_type value_;
+  database_type value_;
   size_t size_{};
   basic_type type_{basic_type::Null};