removed class query and moved their static methods to simple functions

test/backends/TableSequenceFixture.cpp

@@ -12,7 +12,7 @@ TableSequenceFixture::TableSequenceFixture()
 : db(connection::dns) {
   REQUIRE(db.open());
 
-  REQUIRE(query::query::create()
+  REQUIRE(query::create()
     .table(sequence_table_name)
     .columns({
       query::column("name", utils::basic_type::Varchar, 255),
@@ -22,7 +22,7 @@ TableSequenceFixture::TableSequenceFixture()
 }
 
 TableSequenceFixture::~TableSequenceFixture() {
-  REQUIRE(query::query::drop()
+  REQUIRE(query::drop()
     .table(sequence_table_name)
     .execute(db));
   REQUIRE(db.close());