added returning token for insert query

test/backends/QueryTest.cpp

@@ -87,6 +87,30 @@ TEST_CASE_METHOD(QueryFixture, "Execute select statement with where clause", "[q
   }
 }
 
+TEST_CASE_METHOD(QueryFixture, "Execute insert with returning", "[query][insert][returning]") {
+  REQUIRE(repo.attach<person>("persons"));
+  auto result = repo.create(db);
+  REQUIRE(result.is_ok());
+
+  check_table_exists(PERSON.table_name());
+
+  person george{7, "george", 45};
+  george.image.emplace_back(37);
+
+  auto res = query::insert()
+    .into(PERSON, {PERSON.id, PERSON.name, PERSON.age, PERSON.image})
+    .values(george)
+    .returning(PERSON.id)
+    .fetch_one(db);
+  REQUIRE(res.is_ok());
+
+  auto rec = res.release();
+  REQUIRE(rec->size() == 1);
+  REQUIRE(rec->at(0).name() == "persons.id");
+  REQUIRE(rec->at(0).is_integer());
+  REQUIRE(rec->at(0).as<uint32_t>() == 7);
+}
+
 TEST_CASE_METHOD(QueryFixture, "Execute insert statement", "[query][insert]") {
   auto res = query::create()
     .table("person")