From df8e2b6c81ef99515c515d54630b0582fefb2019 Mon Sep 17 00:00:00 2001
From: Roland Bock <rbock@eudoxos.de>
Date: Sun, 28 Jul 2024 19:37:39 +0200
Subject: [PATCH] Move clauses into sub directory

---
 .../{in_fwd.h => aggregate_function.h}        |  12 +-
 .../avg.h                                     |   0
 .../count.h                                   |   2 +-
 .../max.h                                     |   0
 .../min.h                                     |   0
 .../sum.h                                     |   0
 include/sqlpp11/aggregate_functions.h         |  33 ---
 include/sqlpp11/{ => clause}/for_update.h     |   0
 include/sqlpp11/{ => clause}/from.h           |   0
 include/sqlpp11/{ => clause}/group_by.h       |   0
 include/sqlpp11/{ => clause}/having.h         |   0
 include/sqlpp11/{ => clause}/insert.h         |   4 +-
 include/sqlpp11/{ => clause}/insert_value.h   |   0
 .../sqlpp11/{ => clause}/insert_value_list.h  |   2 +-
 include/sqlpp11/{ => clause}/into.h           |   0
 include/sqlpp11/{ => clause}/limit.h          |   0
 include/sqlpp11/{ => clause}/offset.h         |   0
 include/sqlpp11/{ => clause}/order_by.h       |   0
 include/sqlpp11/{ => clause}/remove.h         |   6 +-
 include/sqlpp11/{ => clause}/select.h         |  24 +--
 include/sqlpp11/{ => clause}/select_as.h      |   0
 .../sqlpp11/{ => clause}/select_column_list.h |   4 +-
 .../{ => clause}/select_column_traits.h       |   0
 .../sqlpp11/{ => clause}/select_flag_list.h   |   2 +-
 include/sqlpp11/{ => clause}/select_flags.h   |   0
 include/sqlpp11/{ => clause}/update.h         |   4 +-
 include/sqlpp11/{ => clause}/update_list.h    |   0
 include/sqlpp11/{ => clause}/using.h          |   0
 include/sqlpp11/{ => clause}/where.h          |   0
 include/sqlpp11/{ => clause}/with.h           |   0
 include/sqlpp11/cte.h                         |  10 +-
 include/sqlpp11/field_spec.h                  |   2 +-
 include/sqlpp11/{functions.h => function.h}   |   8 +-
 include/sqlpp11/is_null_fwd.h                 |  35 ----
 include/sqlpp11/lower.h                       |  72 -------
 include/sqlpp11/mysql/bind_result.h           |   2 +-
 include/sqlpp11/mysql/char_result.h           |   2 +-
 include/sqlpp11/mysql/connection.h            |   4 +-
 include/sqlpp11/mysql/prepared_statement.h    |   2 +-
 include/sqlpp11/mysql/remove.h                |   6 +-
 include/sqlpp11/mysql/serializer.h            |   2 +-
 include/sqlpp11/mysql/update.h                |   6 +-
 include/sqlpp11/operator/as_expression.h      |   2 +-
 include/sqlpp11/postgresql/bind_result.h      |   2 +-
 include/sqlpp11/postgresql/exception.h        |   2 +-
 include/sqlpp11/postgresql/insert.h           |   2 +-
 include/sqlpp11/postgresql/on_conflict.h      |   2 +-
 .../postgresql/on_conflict_do_update.h        |   2 +-
 include/sqlpp11/postgresql/postgresql.h       |   6 +-
 .../sqlpp11/postgresql/prepared_statement.h   |   2 +-
 include/sqlpp11/postgresql/remove.h           |   2 +-
 include/sqlpp11/postgresql/returning.h        |   2 +-
 include/sqlpp11/postgresql/update.h           |   2 +-
 include/sqlpp11/sqlite3/bind_result.h         |   2 +-
 include/sqlpp11/sqlite3/insert_or.h           |   4 +-
 include/sqlpp11/sqlite3/prepared_statement.h  |   2 +-
 include/sqlpp11/sqlite3/serializer.h          |   2 +-
 include/sqlpp11/sqlpp11.h                     |  11 +-
 include/sqlpp11/trim.h                        |  80 -------
 include/sqlpp11/union.h                       | 197 ------------------
 include/sqlpp11/upper.h                       |  72 -------
 include/sqlpp11/without_table_check.h         |  60 ------
 tests/core/constraints/must_not_insert.cpp    |   2 +-
 tests/core/constraints/must_not_update.cpp    |   2 +-
 tests/core/constraints/require_insert.cpp     |   2 +-
 tests/core/static_asserts/aggregates.cpp      |   2 +-
 tests/core/types/CMakeLists.txt               |   2 +-
 ...e_functions.cpp => aggregate_function.cpp} |   0
 tests/core/types/dynamic.cpp                  |   4 +-
 tests/core/types/select_as.cpp                |  14 +-
 tests/core/usage/Function.cpp                 |   2 +-
 tests/core/usage/Insert.cpp                   |   4 +-
 tests/core/usage/Prepared.cpp                 |   2 +-
 tests/core/usage/Select.cpp                   |   3 +-
 tests/core/usage/SelectType.cpp               |   3 +-
 tests/core/usage/Union.cpp                    |   2 +-
 tests/core/usage/With.cpp                     |   2 +-
 tests/include/ConnectionPoolTests.h           |   2 +-
 tests/mysql/usage/DynamicSelect.cpp           |   8 +-
 tests/mysql/usage/MoveConstructor.cpp         |   8 +-
 tests/mysql/usage/Prepared.cpp                |   8 +-
 tests/mysql/usage/Select.cpp                  |   8 +-
 tests/mysql/usage/Truncated.cpp               |   8 +-
 tests/sqlite3/usage/DynamicLoadingTest.cpp    |   8 +-
 tests/sqlite3/usage/DynamicSelect.cpp         |   8 +-
 tests/sqlite3/usage/Select.cpp                |   8 +-
 tests/sqlite3/usage/Transaction.cpp           |   8 +-
 87 files changed, 136 insertions(+), 684 deletions(-)
 rename include/sqlpp11/{in_fwd.h => aggregate_function.h} (86%)
 rename include/sqlpp11/{aggregate_functions => aggregate_function}/avg.h (100%)
 rename include/sqlpp11/{aggregate_functions => aggregate_function}/count.h (98%)
 rename include/sqlpp11/{aggregate_functions => aggregate_function}/max.h (100%)
 rename include/sqlpp11/{aggregate_functions => aggregate_function}/min.h (100%)
 rename include/sqlpp11/{aggregate_functions => aggregate_function}/sum.h (100%)
 delete mode 100644 include/sqlpp11/aggregate_functions.h
 rename include/sqlpp11/{ => clause}/for_update.h (100%)
 rename include/sqlpp11/{ => clause}/from.h (100%)
 rename include/sqlpp11/{ => clause}/group_by.h (100%)
 rename include/sqlpp11/{ => clause}/having.h (100%)
 rename include/sqlpp11/{ => clause}/insert.h (97%)
 rename include/sqlpp11/{ => clause}/insert_value.h (100%)
 rename include/sqlpp11/{ => clause}/insert_value_list.h (99%)
 rename include/sqlpp11/{ => clause}/into.h (100%)
 rename include/sqlpp11/{ => clause}/limit.h (100%)
 rename include/sqlpp11/{ => clause}/offset.h (100%)
 rename include/sqlpp11/{ => clause}/order_by.h (100%)
 rename include/sqlpp11/{ => clause}/remove.h (97%)
 rename include/sqlpp11/{ => clause}/select.h (86%)
 rename include/sqlpp11/{ => clause}/select_as.h (100%)
 rename include/sqlpp11/{ => clause}/select_column_list.h (99%)
 rename include/sqlpp11/{ => clause}/select_column_traits.h (100%)
 rename include/sqlpp11/{ => clause}/select_flag_list.h (99%)
 rename include/sqlpp11/{ => clause}/select_flags.h (100%)
 rename include/sqlpp11/{ => clause}/update.h (97%)
 rename include/sqlpp11/{ => clause}/update_list.h (100%)
 rename include/sqlpp11/{ => clause}/using.h (100%)
 rename include/sqlpp11/{ => clause}/where.h (100%)
 rename include/sqlpp11/{ => clause}/with.h (100%)
 rename include/sqlpp11/{functions.h => function.h} (94%)
 delete mode 100644 include/sqlpp11/is_null_fwd.h
 delete mode 100644 include/sqlpp11/lower.h
 delete mode 100644 include/sqlpp11/trim.h
 delete mode 100644 include/sqlpp11/union.h
 delete mode 100644 include/sqlpp11/upper.h
 delete mode 100644 include/sqlpp11/without_table_check.h
 rename tests/core/types/{aggregate_functions.cpp => aggregate_function.cpp} (100%)

diff --git a/include/sqlpp11/in_fwd.h b/include/sqlpp11/aggregate_function.h
similarity index 86%
rename from include/sqlpp11/in_fwd.h
rename to include/sqlpp11/aggregate_function.h
index cceeba81..6ddc12fd 100644
--- a/include/sqlpp11/in_fwd.h
+++ b/include/sqlpp11/aggregate_function.h
@@ -26,10 +26,8 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-namespace sqlpp
-{
-  template <typename Operand, typename... Args>
-  struct in_t;
-  template <typename Operand, typename... Args>
-  struct not_in_t;
-}  // namespace sqlpp
+#include <sqlpp11/aggregate_function/count.h>
+#include <sqlpp11/aggregate_function/min.h>
+#include <sqlpp11/aggregate_function/max.h>
+#include <sqlpp11/aggregate_function/avg.h>
+#include <sqlpp11/aggregate_function/sum.h>
diff --git a/include/sqlpp11/aggregate_functions/avg.h b/include/sqlpp11/aggregate_function/avg.h
similarity index 100%
rename from include/sqlpp11/aggregate_functions/avg.h
rename to include/sqlpp11/aggregate_function/avg.h
diff --git a/include/sqlpp11/aggregate_functions/count.h b/include/sqlpp11/aggregate_function/count.h
similarity index 98%
rename from include/sqlpp11/aggregate_functions/count.h
rename to include/sqlpp11/aggregate_function/count.h
index 2ab43135..b2d3a514 100644
--- a/include/sqlpp11/aggregate_functions/count.h
+++ b/include/sqlpp11/aggregate_function/count.h
@@ -28,7 +28,7 @@
 
 #include <sqlpp11/enable_as.h>
 #include <sqlpp11/enable_over.h>
-#include <sqlpp11/select_flags.h>
+#include <sqlpp11/clause/select_flags.h>
 #include <sqlpp11/aggregate_function_operators.h>
 #include <sqlpp11/type_traits.h>
 
diff --git a/include/sqlpp11/aggregate_functions/max.h b/include/sqlpp11/aggregate_function/max.h
similarity index 100%
rename from include/sqlpp11/aggregate_functions/max.h
rename to include/sqlpp11/aggregate_function/max.h
diff --git a/include/sqlpp11/aggregate_functions/min.h b/include/sqlpp11/aggregate_function/min.h
similarity index 100%
rename from include/sqlpp11/aggregate_functions/min.h
rename to include/sqlpp11/aggregate_function/min.h
diff --git a/include/sqlpp11/aggregate_functions/sum.h b/include/sqlpp11/aggregate_function/sum.h
similarity index 100%
rename from include/sqlpp11/aggregate_functions/sum.h
rename to include/sqlpp11/aggregate_function/sum.h
diff --git a/include/sqlpp11/aggregate_functions.h b/include/sqlpp11/aggregate_functions.h
deleted file mode 100644
index f39903e2..00000000
--- a/include/sqlpp11/aggregate_functions.h
+++ /dev/null
@@ -1,33 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2013-2015, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/aggregate_functions/count.h>
-#include <sqlpp11/aggregate_functions/min.h>
-#include <sqlpp11/aggregate_functions/max.h>
-#include <sqlpp11/aggregate_functions/avg.h>
-#include <sqlpp11/aggregate_functions/sum.h>
diff --git a/include/sqlpp11/for_update.h b/include/sqlpp11/clause/for_update.h
similarity index 100%
rename from include/sqlpp11/for_update.h
rename to include/sqlpp11/clause/for_update.h
diff --git a/include/sqlpp11/from.h b/include/sqlpp11/clause/from.h
similarity index 100%
rename from include/sqlpp11/from.h
rename to include/sqlpp11/clause/from.h
diff --git a/include/sqlpp11/group_by.h b/include/sqlpp11/clause/group_by.h
similarity index 100%
rename from include/sqlpp11/group_by.h
rename to include/sqlpp11/clause/group_by.h
diff --git a/include/sqlpp11/having.h b/include/sqlpp11/clause/having.h
similarity index 100%
rename from include/sqlpp11/having.h
rename to include/sqlpp11/clause/having.h
diff --git a/include/sqlpp11/insert.h b/include/sqlpp11/clause/insert.h
similarity index 97%
rename from include/sqlpp11/insert.h
rename to include/sqlpp11/clause/insert.h
index 2161885a..5d01845f 100644
--- a/include/sqlpp11/insert.h
+++ b/include/sqlpp11/clause/insert.h
@@ -33,8 +33,8 @@
 #include <sqlpp11/prepared_insert.h>
 #include <sqlpp11/default_value.h>
 #include <sqlpp11/noop.h>
-#include <sqlpp11/into.h>
-#include <sqlpp11/insert_value_list.h>
+#include <sqlpp11/clause/into.h>
+#include <sqlpp11/clause/insert_value_list.h>
 
 namespace sqlpp
 {
diff --git a/include/sqlpp11/insert_value.h b/include/sqlpp11/clause/insert_value.h
similarity index 100%
rename from include/sqlpp11/insert_value.h
rename to include/sqlpp11/clause/insert_value.h
diff --git a/include/sqlpp11/insert_value_list.h b/include/sqlpp11/clause/insert_value_list.h
similarity index 99%
rename from include/sqlpp11/insert_value_list.h
rename to include/sqlpp11/clause/insert_value_list.h
index 95b18bc6..50528f9e 100644
--- a/include/sqlpp11/insert_value_list.h
+++ b/include/sqlpp11/clause/insert_value_list.h
@@ -28,7 +28,7 @@
 
 #include <sqlpp11/operator/assign_expression.h>
 #include <sqlpp11/column_fwd.h>
-#include <sqlpp11/insert_value.h>
+#include <sqlpp11/clause/insert_value.h>
 #include <sqlpp11/interpret_tuple.h>
 #include <sqlpp11/logic.h>
 #include <sqlpp11/no_data.h>
diff --git a/include/sqlpp11/into.h b/include/sqlpp11/clause/into.h
similarity index 100%
rename from include/sqlpp11/into.h
rename to include/sqlpp11/clause/into.h
diff --git a/include/sqlpp11/limit.h b/include/sqlpp11/clause/limit.h
similarity index 100%
rename from include/sqlpp11/limit.h
rename to include/sqlpp11/clause/limit.h
diff --git a/include/sqlpp11/offset.h b/include/sqlpp11/clause/offset.h
similarity index 100%
rename from include/sqlpp11/offset.h
rename to include/sqlpp11/clause/offset.h
diff --git a/include/sqlpp11/order_by.h b/include/sqlpp11/clause/order_by.h
similarity index 100%
rename from include/sqlpp11/order_by.h
rename to include/sqlpp11/clause/order_by.h
diff --git a/include/sqlpp11/remove.h b/include/sqlpp11/clause/remove.h
similarity index 97%
rename from include/sqlpp11/remove.h
rename to include/sqlpp11/clause/remove.h
index f06631fe..7edc5b26 100644
--- a/include/sqlpp11/remove.h
+++ b/include/sqlpp11/clause/remove.h
@@ -32,9 +32,9 @@
 #include <sqlpp11/parameter_list.h>
 #include <sqlpp11/prepared_remove.h>
 #include <sqlpp11/noop.h>
-#include <sqlpp11/from.h>
-#include <sqlpp11/using.h>
-#include <sqlpp11/where.h>
+#include <sqlpp11/clause/from.h>
+#include <sqlpp11/clause/using.h>
+#include <sqlpp11/clause/where.h>
 
 namespace sqlpp
 {
diff --git a/include/sqlpp11/select.h b/include/sqlpp11/clause/select.h
similarity index 86%
rename from include/sqlpp11/select.h
rename to include/sqlpp11/clause/select.h
index 318f68a1..7a8adceb 100644
--- a/include/sqlpp11/select.h
+++ b/include/sqlpp11/clause/select.h
@@ -30,18 +30,18 @@
 
 #include <sqlpp11/noop.h>
 #include <sqlpp11/connection.h>
-#include <sqlpp11/with.h>
-#include <sqlpp11/select_flag_list.h>
-#include <sqlpp11/select_column_list.h>
-#include <sqlpp11/from.h>
-#include <sqlpp11/where.h>
-#include <sqlpp11/group_by.h>
-#include <sqlpp11/having.h>
-#include <sqlpp11/order_by.h>
-#include <sqlpp11/limit.h>
-#include <sqlpp11/for_update.h>
-#include <sqlpp11/offset.h>
-#include <sqlpp11/union.h>
+#include <sqlpp11/clause/with.h>
+#include <sqlpp11/clause/select_flag_list.h>
+#include <sqlpp11/clause/select_column_list.h>
+#include <sqlpp11/clause/from.h>
+#include <sqlpp11/clause/where.h>
+#include <sqlpp11/clause/group_by.h>
+#include <sqlpp11/clause/having.h>
+#include <sqlpp11/clause/order_by.h>
+#include <sqlpp11/clause/limit.h>
+#include <sqlpp11/clause/for_update.h>
+#include <sqlpp11/clause/offset.h>
+#include <sqlpp11/clause/union.h>
 #include <sqlpp11/wrong.h>
 
 namespace sqlpp
diff --git a/include/sqlpp11/select_as.h b/include/sqlpp11/clause/select_as.h
similarity index 100%
rename from include/sqlpp11/select_as.h
rename to include/sqlpp11/clause/select_as.h
diff --git a/include/sqlpp11/select_column_list.h b/include/sqlpp11/clause/select_column_list.h
similarity index 99%
rename from include/sqlpp11/select_column_list.h
rename to include/sqlpp11/clause/select_column_list.h
index 8d3135c0..d7dff79f 100644
--- a/include/sqlpp11/select_column_list.h
+++ b/include/sqlpp11/clause/select_column_list.h
@@ -33,8 +33,8 @@
 #include <sqlpp11/interpret_tuple.h>
 #include <sqlpp11/policy_update.h>
 #include <sqlpp11/result_row.h>
-#include <sqlpp11/select_as.h>
-#include <sqlpp11/select_column_traits.h>
+#include <sqlpp11/clause/select_as.h>
+#include <sqlpp11/clause/select_column_traits.h>
 #include <sqlpp11/table.h>
 #include <tuple>
 
diff --git a/include/sqlpp11/select_column_traits.h b/include/sqlpp11/clause/select_column_traits.h
similarity index 100%
rename from include/sqlpp11/select_column_traits.h
rename to include/sqlpp11/clause/select_column_traits.h
diff --git a/include/sqlpp11/select_flag_list.h b/include/sqlpp11/clause/select_flag_list.h
similarity index 99%
rename from include/sqlpp11/select_flag_list.h
rename to include/sqlpp11/clause/select_flag_list.h
index 06b3a69b..5dc346ac 100644
--- a/include/sqlpp11/select_flag_list.h
+++ b/include/sqlpp11/clause/select_flag_list.h
@@ -30,7 +30,7 @@
 #include <sqlpp11/interpret_tuple.h>
 #include <sqlpp11/no_data.h>
 #include <sqlpp11/policy_update.h>
-#include <sqlpp11/select_flags.h>
+#include <sqlpp11/clause/select_flags.h>
 #include <sqlpp11/type_traits.h>
 #include <tuple>
 
diff --git a/include/sqlpp11/select_flags.h b/include/sqlpp11/clause/select_flags.h
similarity index 100%
rename from include/sqlpp11/select_flags.h
rename to include/sqlpp11/clause/select_flags.h
diff --git a/include/sqlpp11/update.h b/include/sqlpp11/clause/update.h
similarity index 97%
rename from include/sqlpp11/update.h
rename to include/sqlpp11/clause/update.h
index 717ab3ca..8b408237 100644
--- a/include/sqlpp11/update.h
+++ b/include/sqlpp11/clause/update.h
@@ -32,9 +32,9 @@
 #include <sqlpp11/parameter_list.h>
 #include <sqlpp11/prepared_update.h>
 #include <sqlpp11/single_table.h>
-#include <sqlpp11/update_list.h>
+#include <sqlpp11/clause/update_list.h>
 #include <sqlpp11/noop.h>
-#include <sqlpp11/where.h>
+#include <sqlpp11/clause/where.h>
 
 namespace sqlpp
 {
diff --git a/include/sqlpp11/update_list.h b/include/sqlpp11/clause/update_list.h
similarity index 100%
rename from include/sqlpp11/update_list.h
rename to include/sqlpp11/clause/update_list.h
diff --git a/include/sqlpp11/using.h b/include/sqlpp11/clause/using.h
similarity index 100%
rename from include/sqlpp11/using.h
rename to include/sqlpp11/clause/using.h
diff --git a/include/sqlpp11/where.h b/include/sqlpp11/clause/where.h
similarity index 100%
rename from include/sqlpp11/where.h
rename to include/sqlpp11/clause/where.h
diff --git a/include/sqlpp11/with.h b/include/sqlpp11/clause/with.h
similarity index 100%
rename from include/sqlpp11/with.h
rename to include/sqlpp11/clause/with.h
diff --git a/include/sqlpp11/cte.h b/include/sqlpp11/cte.h
index 30b18e33..09337598 100644
--- a/include/sqlpp11/cte.h
+++ b/include/sqlpp11/cte.h
@@ -30,7 +30,7 @@
 #include <sqlpp11/logic.h>
 #include <sqlpp11/parameter_list.h>
 #include <sqlpp11/result_row.h>
-#include <sqlpp11/select_flags.h>
+#include <sqlpp11/clause/select_flags.h>
 #include <sqlpp11/statement_fwd.h>
 #include <sqlpp11/table_ref.h>
 #include <sqlpp11/type_traits.h>
@@ -169,10 +169,10 @@ namespace sqlpp
     {
       static_assert(is_statement_t<Rhs>::value, "argument of union call has to be a statement");
       static_assert(has_policy_t<Rhs, is_select_t>::value, "argument of union call has to be a select");
-      static_assert(has_result_row_t<Rhs>::value, "argument of a union has to be a (complete) select statement");
+      static_assert(has_result_row_t<Rhs>::value, "argument of a clause/union.has to be a (complete) select statement");
 
       static_assert(std::is_same<_result_row_t, get_result_row_t<Rhs>>::value,
-                    "both select statements in a union have to have the same result columns (type and name)");
+                    "both select statements in a clause/union.have to have the same result columns (type and name)");
 
       return _union_impl<void, distinct_t>(check_cte_union_t<Rhs>{}, rhs);
     }
@@ -184,10 +184,10 @@ namespace sqlpp
     {
       static_assert(is_statement_t<Rhs>::value, "argument of union call has to be a statement");
       static_assert(has_policy_t<Rhs, is_select_t>::value, "argument of union call has to be a select");
-      static_assert(has_result_row_t<Rhs>::value, "argument of a union has to be a (complete) select statement");
+      static_assert(has_result_row_t<Rhs>::value, "argument of a clause/union.has to be a (complete) select statement");
 
       static_assert(std::is_same<_result_row_t, get_result_row_t<Rhs>>::value,
-                    "both select statements in a union have to have the same result columns (type and name)");
+                    "both select statements in a clause/union.have to have the same result columns (type and name)");
 
       return _union_impl<all_t>(check_cte_union_t<Rhs>{}, rhs);
     }
diff --git a/include/sqlpp11/field_spec.h b/include/sqlpp11/field_spec.h
index 3bf3dbe7..8b1d25c7 100644
--- a/include/sqlpp11/field_spec.h
+++ b/include/sqlpp11/field_spec.h
@@ -29,7 +29,7 @@
 #include <type_traits>
 
 #include <sqlpp11/type_traits.h>
-#include <sqlpp11/select_column_traits.h>
+#include <sqlpp11/clause/select_column_traits.h>
 
 namespace sqlpp
 {
diff --git a/include/sqlpp11/functions.h b/include/sqlpp11/function.h
similarity index 94%
rename from include/sqlpp11/functions.h
rename to include/sqlpp11/function.h
index e5d2999f..98268aee 100644
--- a/include/sqlpp11/functions.h
+++ b/include/sqlpp11/function.h
@@ -30,11 +30,11 @@
 #include <sqlpp11/noop.h>
 #include <sqlpp11/parameter.h>
 #include <sqlpp11/parameter_list.h>
-#include <sqlpp11/aggregate_functions.h>
-#include <sqlpp11/trim.h>
+#include <sqlpp11/aggregate_function.h>
+#include <sqlpp11/function/trim.h>
 #include <sqlpp11/case.h>
-#include <sqlpp11/lower.h>
-#include <sqlpp11/upper.h>
+#include <sqlpp11/function/lower.h>
+#include <sqlpp11/function/upper.h>
 #include <sqlpp11/value_type.h>
 #include <sqlpp11/verbatim.h>  // Csaba Csoma suggests: unsafe_sql instead of verbatim
 #include <sqlpp11/parameterized_verbatim.h>
diff --git a/include/sqlpp11/is_null_fwd.h b/include/sqlpp11/is_null_fwd.h
deleted file mode 100644
index 888ff84a..00000000
--- a/include/sqlpp11/is_null_fwd.h
+++ /dev/null
@@ -1,35 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2013-2015, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-namespace sqlpp
-{
-  template <typename Operand>
-  struct is_null_t;
-  template <typename Operand>
-  struct is_not_null_t;
-}  // namespace sqlpp
diff --git a/include/sqlpp11/lower.h b/include/sqlpp11/lower.h
deleted file mode 100644
index 4f30e177..00000000
--- a/include/sqlpp11/lower.h
+++ /dev/null
@@ -1,72 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2023, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/serialize.h>
-#include <sqlpp11/type_traits.h>
-
-namespace sqlpp
-{
-  template <typename Expr>
-  struct lower_t
-  {
-    using _traits = make_traits<text, tag::is_expression, tag::is_selectable>;
-
-    using _nodes = detail::type_vector<Expr>;
-
-    lower_t(const Expr expr) : _expr(expr)
-    {
-    }
-
-    lower_t(const lower_t&) = default;
-    lower_t(lower_t&&) = default;
-    lower_t& operator=(const lower_t&) = default;
-    lower_t& operator=(lower_t&&) = default;
-    ~lower_t() = default;
-
-    Expr _expr;
-  };
-
-  template <typename Context, typename Expr>
-  Context& serialize(Context& context, const lower_t<Expr>& t)
-  {
-    context << "LOWER(";
-    serialize_operand(context, t._expr);
-    context << ")";
-    return context;
-  }
-
-  template<typename T>
-    using check_lower_args = std::enable_if_t<is_text<T>::value>;
-
-  template <typename T, typename = check_lower_args<T>>
-  auto lower(T t) -> lower_t<T>
-  {
-    return {std::move(t)};
-  }
-
-}  // namespace sqlpp
diff --git a/include/sqlpp11/mysql/bind_result.h b/include/sqlpp11/mysql/bind_result.h
index 9e3245cf..d56bc585 100644
--- a/include/sqlpp11/mysql/bind_result.h
+++ b/include/sqlpp11/mysql/bind_result.h
@@ -55,7 +55,7 @@ namespace sqlpp
       bind_result_t(const std::shared_ptr<detail::prepared_statement_handle_t>& handle) : _handle{handle}
       {
         if (_handle and _handle->debug)
-          std::cerr << "MySQL debug: Constructing bind result, using handle at " << _handle.get() << std::endl;
+          std::cerr << "MySQL debug: Constructing bind result, clause/using.handle at " << _handle.get() << std::endl;
       }
       bind_result_t(const bind_result_t&) = delete;
       bind_result_t(bind_result_t&& rhs) = default;
diff --git a/include/sqlpp11/mysql/char_result.h b/include/sqlpp11/mysql/char_result.h
index 73031192..75a35cf1 100644
--- a/include/sqlpp11/mysql/char_result.h
+++ b/include/sqlpp11/mysql/char_result.h
@@ -57,7 +57,7 @@ namespace sqlpp
           throw sqlpp::exception{"MySQL: Constructing char_result without valid handle"};
 
         if (_handle->debug)
-          std::cerr << "MySQL debug: Constructing result, using handle at " << _handle.get() << std::endl;
+          std::cerr << "MySQL debug: Constructing result, clause/using.handle at " << _handle.get() << std::endl;
       }
 
       char_result_t(const char_result_t&) = delete;
diff --git a/include/sqlpp11/mysql/connection.h b/include/sqlpp11/mysql/connection.h
index 9a7b1ea0..94991a9c 100644
--- a/include/sqlpp11/mysql/connection.h
+++ b/include/sqlpp11/mysql/connection.h
@@ -35,8 +35,8 @@
 #include <sqlpp11/mysql/connection_config.h>
 #include <sqlpp11/mysql/detail/connection_handle.h>
 #include <sqlpp11/mysql/prepared_statement.h>
-#include <sqlpp11/mysql/remove.h>
-#include <sqlpp11/mysql/update.h>
+#include <sqlpp11/mysql/clause/remove.h>
+#include <sqlpp11/mysql/clause/update.h>
 #include <sqlpp11/serialize.h>
 #include <iostream>
 #include <sstream>
diff --git a/include/sqlpp11/mysql/prepared_statement.h b/include/sqlpp11/mysql/prepared_statement.h
index 6e3d6fe0..4795350b 100644
--- a/include/sqlpp11/mysql/prepared_statement.h
+++ b/include/sqlpp11/mysql/prepared_statement.h
@@ -51,7 +51,7 @@ namespace sqlpp
       prepared_statement_t(std::shared_ptr<detail::prepared_statement_handle_t>&& handle) : _handle{std::move(handle)}
       {
         if (_handle and _handle->debug)
-          std::cerr << "MySQL debug: Constructing prepared_statement, using handle at " << _handle.get() << std::endl;
+          std::cerr << "MySQL debug: Constructing prepared_statement, clause/using.handle at " << _handle.get() << std::endl;
       }
 
       prepared_statement_t(const prepared_statement_t&) = delete;
diff --git a/include/sqlpp11/mysql/remove.h b/include/sqlpp11/mysql/remove.h
index c24be9e6..1e7cf32b 100644
--- a/include/sqlpp11/mysql/remove.h
+++ b/include/sqlpp11/mysql/remove.h
@@ -26,9 +26,9 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/remove.h>
-#include <sqlpp11/order_by.h>
-#include <sqlpp11/limit.h>
+#include <sqlpp11/clause/remove.h>
+#include <sqlpp11/clause/order_by.h>
+#include <sqlpp11/clause/clause/limit.h>
 
 namespace sqlpp
 {
diff --git a/include/sqlpp11/mysql/serializer.h b/include/sqlpp11/mysql/serializer.h
index 9f8f07bc..466430f6 100644
--- a/include/sqlpp11/mysql/serializer.h
+++ b/include/sqlpp11/mysql/serializer.h
@@ -27,7 +27,7 @@
  */
 
 #include <sqlpp11/data_types/text/concat.h>
-#include <sqlpp11/insert_value_list.h>
+#include <sqlpp11/clause/insert_value_list.h>
 
 namespace sqlpp
 {
diff --git a/include/sqlpp11/mysql/update.h b/include/sqlpp11/mysql/update.h
index bc0a24fc..3fb7d43e 100644
--- a/include/sqlpp11/mysql/update.h
+++ b/include/sqlpp11/mysql/update.h
@@ -26,9 +26,9 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/update.h>
-#include <sqlpp11/limit.h>
-#include <sqlpp11/order_by.h>
+#include <sqlpp11/clause/update.h>
+#include <sqlpp11/clause/clause/limit.h>
+#include <sqlpp11/clause/order_by.h>
 
 namespace sqlpp
 {
diff --git a/include/sqlpp11/operator/as_expression.h b/include/sqlpp11/operator/as_expression.h
index 4099202c..3f90dc42 100644
--- a/include/sqlpp11/operator/as_expression.h
+++ b/include/sqlpp11/operator/as_expression.h
@@ -69,7 +69,7 @@ namespace sqlpp
   {
     serialize_operand(context, t._expression);
     context << " AS ";
-    context << name_tag_of_t<as_expression<Expression, AliasProvider>>::_name_t::template char_ptr<Context>();
+    context << name_tag_of_t<AliasProvider>::_name_t::template char_ptr<Context>();
     return context;
   }
   template <typename Expr, typename AliasProvider>
diff --git a/include/sqlpp11/postgresql/bind_result.h b/include/sqlpp11/postgresql/bind_result.h
index 6079f4a4..69013673 100644
--- a/include/sqlpp11/postgresql/bind_result.h
+++ b/include/sqlpp11/postgresql/bind_result.h
@@ -155,7 +155,7 @@ namespace sqlpp
         _var_buffers.resize(_handle->result.field_count());
         if (this->_handle && this->_handle->debug())
         {
-          std::cerr << "PostgreSQL debug: constructing bind result, using handle at: " << this->_handle.get()
+          std::cerr << "PostgreSQL debug: constructing bind result, clause/using.handle at: " << this->_handle.get()
                     << std::endl;
         }
       }
diff --git a/include/sqlpp11/postgresql/exception.h b/include/sqlpp11/postgresql/exception.h
index 30ed6d2b..174124ef 100644
--- a/include/sqlpp11/postgresql/exception.h
+++ b/include/sqlpp11/postgresql/exception.h
@@ -28,7 +28,7 @@
  */
 
 /**
-  classes copied from http://pqxx.org/devprojects/libpqxx/doc/3.1/html/Reference/a00032.html
+  classes copied clause/from.http://pqxx.org/devprojects/libpqxx/doc/3.1/html/Reference/a00032.html
 */
 
 #include "visibility.h"
diff --git a/include/sqlpp11/postgresql/insert.h b/include/sqlpp11/postgresql/insert.h
index 7adaf98d..c3009a0a 100644
--- a/include/sqlpp11/postgresql/insert.h
+++ b/include/sqlpp11/postgresql/insert.h
@@ -26,7 +26,7 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/insert.h>
+#include <sqlpp11/clause/insert.h>
 #include <sqlpp11/postgresql/on_conflict.h>
 #include <sqlpp11/postgresql/returning.h>
 
diff --git a/include/sqlpp11/postgresql/on_conflict.h b/include/sqlpp11/postgresql/on_conflict.h
index 670e72fc..a86aca07 100644
--- a/include/sqlpp11/postgresql/on_conflict.h
+++ b/include/sqlpp11/postgresql/on_conflict.h
@@ -28,7 +28,7 @@
  */
 
 #include <sqlpp11/postgresql/on_conflict_do_nothing.h>
-#include <sqlpp11/postgresql/on_conflict_do_update.h>
+#include <sqlpp11/postgresql/on_conflict_do_clause/update.h>
 #include <sqlpp11/statement.h>
 
 namespace sqlpp
diff --git a/include/sqlpp11/postgresql/on_conflict_do_update.h b/include/sqlpp11/postgresql/on_conflict_do_update.h
index cc02811f..8fbe8ad4 100644
--- a/include/sqlpp11/postgresql/on_conflict_do_update.h
+++ b/include/sqlpp11/postgresql/on_conflict_do_update.h
@@ -30,7 +30,7 @@
 #include <sqlpp11/detail/type_set.h>
 #include <sqlpp11/interpret_tuple.h>
 #include <sqlpp11/type_traits.h>
-#include <sqlpp11/where.h>
+#include <sqlpp11/clause/where.h>
 
 namespace sqlpp
 {
diff --git a/include/sqlpp11/postgresql/postgresql.h b/include/sqlpp11/postgresql/postgresql.h
index 0dcd1d0d..62abb2fb 100644
--- a/include/sqlpp11/postgresql/postgresql.h
+++ b/include/sqlpp11/postgresql/postgresql.h
@@ -31,6 +31,6 @@
 #include <sqlpp11/postgresql/connection.h>
 #include <sqlpp11/postgresql/connection_pool.h>
 #include <sqlpp11/postgresql/exception.h>
-#include <sqlpp11/postgresql/insert.h>
-#include <sqlpp11/postgresql/remove.h>
-#include <sqlpp11/postgresql/update.h>
+#include <sqlpp11/postgresql/clause/insert.h>
+#include <sqlpp11/postgresql/clause/remove.h>
+#include <sqlpp11/postgresql/clause/update.h>
diff --git a/include/sqlpp11/postgresql/prepared_statement.h b/include/sqlpp11/postgresql/prepared_statement.h
index f160f18e..db73eebf 100644
--- a/include/sqlpp11/postgresql/prepared_statement.h
+++ b/include/sqlpp11/postgresql/prepared_statement.h
@@ -67,7 +67,7 @@ namespace sqlpp
       {
         if (_handle && _handle->debug())
         {
-          std::cerr << "PostgreSQL debug: constructing prepared_statement, using handle at: " << _handle.get()
+          std::cerr << "PostgreSQL debug: constructing prepared_statement, clause/using.handle at: " << _handle.get()
                     << std::endl;
         }
       }
diff --git a/include/sqlpp11/postgresql/remove.h b/include/sqlpp11/postgresql/remove.h
index 5df12402..ac884c8c 100644
--- a/include/sqlpp11/postgresql/remove.h
+++ b/include/sqlpp11/postgresql/remove.h
@@ -26,7 +26,7 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/remove.h>
+#include <sqlpp11/clause/remove.h>
 #include <sqlpp11/postgresql/returning.h>
 
 namespace sqlpp
diff --git a/include/sqlpp11/postgresql/returning.h b/include/sqlpp11/postgresql/returning.h
index 59a6c76a..72bf8ba5 100644
--- a/include/sqlpp11/postgresql/returning.h
+++ b/include/sqlpp11/postgresql/returning.h
@@ -28,7 +28,7 @@
  */
 
 #include <sqlpp11/postgresql/returning_column_list.h>
-#include <sqlpp11/select_column_list.h>
+#include <sqlpp11/clause/select_column_list.h>
 #include <sqlpp11/statement.h>
 
 namespace sqlpp
diff --git a/include/sqlpp11/postgresql/update.h b/include/sqlpp11/postgresql/update.h
index f7a200c2..919d62fc 100644
--- a/include/sqlpp11/postgresql/update.h
+++ b/include/sqlpp11/postgresql/update.h
@@ -26,7 +26,7 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sqlpp11/update.h>
+#include <sqlpp11/clause/update.h>
 #include <sqlpp11/postgresql/returning.h>
 
 namespace sqlpp
diff --git a/include/sqlpp11/sqlite3/bind_result.h b/include/sqlpp11/sqlite3/bind_result.h
index 1bba1463..2c1bfd02 100644
--- a/include/sqlpp11/sqlite3/bind_result.h
+++ b/include/sqlpp11/sqlite3/bind_result.h
@@ -57,7 +57,7 @@ namespace sqlpp
       bind_result_t(const std::shared_ptr<detail::prepared_statement_handle_t>& handle) : _handle{handle}
       {
         if (_handle and _handle->debug)
-          std::cerr << "Sqlite3 debug: Constructing bind result, using handle at " << _handle.get() << std::endl;
+          std::cerr << "Sqlite3 debug: Constructing bind result, clause/using.handle at " << _handle.get() << std::endl;
       }
 
       bind_result_t(const bind_result_t&) = delete;
diff --git a/include/sqlpp11/sqlite3/insert_or.h b/include/sqlpp11/sqlite3/insert_or.h
index 698904d2..144a7658 100644
--- a/include/sqlpp11/sqlite3/insert_or.h
+++ b/include/sqlpp11/sqlite3/insert_or.h
@@ -27,8 +27,8 @@
  */
 
 #include <sqlpp11/default_value.h>
-#include <sqlpp11/insert_value_list.h>
-#include <sqlpp11/into.h>
+#include <sqlpp11/clause/insert_value_list.h>
+#include <sqlpp11/clause/into.h>
 #include <sqlpp11/noop.h>
 #include <sqlpp11/parameter_list.h>
 #include <sqlpp11/prepared_insert.h>
diff --git a/include/sqlpp11/sqlite3/prepared_statement.h b/include/sqlpp11/sqlite3/prepared_statement.h
index daac5e98..dc1fe563 100644
--- a/include/sqlpp11/sqlite3/prepared_statement.h
+++ b/include/sqlpp11/sqlite3/prepared_statement.h
@@ -82,7 +82,7 @@ namespace sqlpp
       prepared_statement_t(std::shared_ptr<detail::prepared_statement_handle_t>&& handle) : _handle(std::move(handle))
       {
         if (_handle and _handle->debug)
-          std::cerr << "Sqlite3 debug: Constructing prepared_statement, using handle at " << _handle.get() << std::endl;
+          std::cerr << "Sqlite3 debug: Constructing prepared_statement, clause/using.handle at " << _handle.get() << std::endl;
       }
       prepared_statement_t(const prepared_statement_t&) = delete;
       prepared_statement_t(prepared_statement_t&& rhs) = default;
diff --git a/include/sqlpp11/sqlite3/serializer.h b/include/sqlpp11/sqlite3/serializer.h
index 0b05fc67..d696529a 100644
--- a/include/sqlpp11/sqlite3/serializer.h
+++ b/include/sqlpp11/sqlite3/serializer.h
@@ -40,7 +40,7 @@
 #include <sqlpp11/parameter.h>
 #include <sqlpp11/pre_join.h>
 #include <sqlpp11/some.h>
-#include <sqlpp11/with.h>
+#include <sqlpp11/clause/with.h>
 
 #include <cmath>
 
diff --git a/include/sqlpp11/sqlpp11.h b/include/sqlpp11/sqlpp11.h
index 57a0afe3..31b54f17 100644
--- a/include/sqlpp11/sqlpp11.h
+++ b/include/sqlpp11/sqlpp11.h
@@ -27,13 +27,12 @@
  */
 
 #include <sqlpp11/alias_provider.h>
-#include <sqlpp11/insert.h>
-#include <sqlpp11/remove.h>
-#include <sqlpp11/update.h>
-#include <sqlpp11/select.h>
-#include <sqlpp11/functions.h>
+#include <sqlpp11/clause/insert.h>
+#include <sqlpp11/clause/remove.h>
+#include <sqlpp11/clause/update.h>
+#include <sqlpp11/clause/select.h>
+#include <sqlpp11/function.h>
 #include <sqlpp11/operator.h>
 #include <sqlpp11/transaction.h>
-#include <sqlpp11/without_table_check.h>
 #include <sqlpp11/schema_qualified_table.h>
 #include <sqlpp11/custom_query.h>
diff --git a/include/sqlpp11/trim.h b/include/sqlpp11/trim.h
deleted file mode 100644
index 68087b6c..00000000
--- a/include/sqlpp11/trim.h
+++ /dev/null
@@ -1,80 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2013-2015, Roland Bock
- * Copyright (c) 2017, Juan Dent
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/serialize.h>
-#include <sqlpp11/type_traits.h>
-
-namespace sqlpp
-{
-  template <typename Expr>
-  struct trim_t
-  {
-    using _traits = make_traits<text, tag::is_expression, tag::is_selectable>;
-
-    trim_t(const Expr expr) : _expr(expr)
-    {
-    }
-
-    trim_t(const trim_t&) = default;
-    trim_t(trim_t&&) = default;
-    trim_t& operator=(const trim_t&) = default;
-    trim_t& operator=(trim_t&&) = default;
-    ~trim_t() = default;
-
-    Expr _expr;
-  };
-
-  template<typename Expr>
-    struct value_type_of<trim_t<Expr>> : public value_type_of<Expr> {};
-
-  template<typename Expr>
-    struct nodes_of<trim_t<Expr>>
-    {
-      using type = detail::type_vector<Expr>;
-    };
-
-  template <typename Context, typename Expr>
-  Context& serialize(Context& context, const trim_t<Expr>& t)
-  {
-    context << "TRIM(";
-    serialize_operand(context, t._expr);
-    context << ")";
-    return context;
-  }
-
-  template<typename T>
-    using check_trim_args = std::enable_if_t<is_text<T>::value>;
-
-  template <typename T, typename = check_trim_args<T>>
-  auto trim(T t) -> trim_t<T>
-  {
-    return {std::move(t)};
-  }
-
-}  // namespace sqlpp
diff --git a/include/sqlpp11/union.h b/include/sqlpp11/union.h
deleted file mode 100644
index ab91aa84..00000000
--- a/include/sqlpp11/union.h
+++ /dev/null
@@ -1,197 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2013-2016, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/interpret_tuple.h>
-#include <sqlpp11/logic.h>
-#include <sqlpp11/parameter_list.h>
-#include <sqlpp11/result_row.h>
-#include <sqlpp11/statement_fwd.h>
-#include <sqlpp11/type_traits.h>
-#include <sqlpp11/union_data.h>
-#include <sqlpp11/union_flags.h>
-
-namespace sqlpp
-{
-  struct no_union_t;
-
-  using blank_union_t = statement_t<no_union_t>;
-  // There is no order by or limit or offset in union, use it as a pseudo table to do that.
-
-  template <typename Check, typename Union>
-  struct union_statement_impl
-  {
-    using type = Check;
-  };
-
-  template <typename Union>
-  struct union_statement_impl<consistent_t, Union>
-  {
-    using type = statement_t<Union, no_union_t>;
-  };
-
-  template <typename Check, typename Union>
-  using union_statement_t = typename union_statement_impl<Check, Union>::type;
-
-  // UNION(EXPR)
-  template <typename Flag, typename Lhs, typename Rhs>
-  struct union_t
-  {
-    using _traits = make_traits<no_value_t, tag::is_union, tag::is_return_value>;
-    using _nodes = detail::type_vector<Lhs, Rhs>;
-
-    using _data_t = union_data_t<Flag, Lhs, Rhs>;
-
-    // Base template to be inherited by the statement
-    template <typename Policies>
-    struct _base_t
-    {
-      _base_t(_data_t data) : _data{std::move(data)}
-      {
-      }
-
-      _data_t _data;
-
-      using _selected_columns_t = typename std::decay<decltype(_data._lhs.get_selected_columns())>::type;
-      _selected_columns_t& get_selected_columns()
-      {
-        return _data._lhs.get_selected_columns();
-      }
-      const _selected_columns_t& get_selected_columns() const
-      {
-        return _data._lhs.get_selected_columns();
-      }
-
-      using _consistency_check = detail::get_first_if<is_inconsistent_t,
-                                                      consistent_t,
-                                                      typename Lhs::_consistency_check,
-                                                      typename Rhs::_consistency_check>;
-    };
-
-    template <typename Statement>
-    using _result_methods_t = typename Lhs::template _result_methods_t<Statement>;
-  };
-
-  SQLPP_PORTABLE_STATIC_ASSERT(assert_union_args_are_statements_t, "arguments for union() must be statements");
-  template <typename... T>
-  struct check_union
-  {
-    using type = static_combined_check_t<
-        static_check_t<logic::all_t<is_statement_t<T>::value...>::value, assert_union_args_are_statements_t>>;
-  };
-  template <typename... T>
-  using check_union_t = typename check_union<T...>::type;
-
-  // NO UNION YET
-  struct no_union_t
-  {
-    using _traits = make_traits<no_value_t, tag::is_union>;
-    using _nodes = detail::type_vector<>;
-
-    // Data
-    using _data_t = no_data_t;
-
-    template <typename Policies>
-    struct _base_t
-    {
-      _base_t() = default;
-      _base_t(_data_t data) : _data{std::move(data)}
-      {
-      }
-
-      _data_t _data;
-
-      template <typename Check, typename T>
-      using _new_statement_t = union_statement_t<Check, T>;
-
-      using _consistency_check = consistent_t;
-
-      template <typename Rhs>
-      auto union_distinct(Rhs rhs) const
-          -> _new_statement_t<check_union_t<derived_statement_t<Policies>, Rhs>,
-                              union_t<union_distinct_t, derived_statement_t<Policies>, Rhs>>
-      {
-        static_assert(is_statement_t<Rhs>::value, "argument of union call has to be a statement");
-        static_assert(has_policy_t<Rhs, is_select_t>::value, "argument of union call has to be a select");
-        static_assert(has_result_row_t<Rhs>::value, "argument of a union has to be a complete select statement");
-        static_assert(has_result_row_t<derived_statement_t<Policies>>::value,
-                      "left hand side argument of a union has to be a complete select statement or union");
-
-        using lhs_result_row_t = get_result_row_t<derived_statement_t<Policies>>;
-        using rhs_result_row_t = get_result_row_t<Rhs>;
-        static_assert(is_result_compatible<lhs_result_row_t, rhs_result_row_t>::value,
-                      "both arguments in a union have to have the same result columns (type and name)");
-
-        return _union_impl<union_distinct_t>(check_union_t<derived_statement_t<Policies>, Rhs>{}, rhs);
-      }
-
-      template <typename Rhs>
-      auto union_all(Rhs rhs) const -> _new_statement_t<check_union_t<derived_statement_t<Policies>, Rhs>,
-                                                        union_t<union_all_t, derived_statement_t<Policies>, Rhs>>
-      {
-        static_assert(is_statement_t<Rhs>::value, "argument of union call has to be a statement");
-        static_assert(has_policy_t<Rhs, is_select_t>::value, "argument of union call has to be a select");
-        static_assert(has_result_row_t<Rhs>::value, "argument of a union has to be a (complete) select statement");
-        static_assert(has_result_row_t<derived_statement_t<Policies>>::value,
-                      "left hand side argument of a union has to be a (complete) select statement");
-
-        using lhs_result_row_t = get_result_row_t<derived_statement_t<Policies>>;
-        using rhs_result_row_t = get_result_row_t<Rhs>;
-        static_assert(is_result_compatible<lhs_result_row_t, rhs_result_row_t>::value,
-                      "both arguments in a union have to have the same result columns (type and name)");
-
-        return _union_impl<union_all_t>(check_union_t<derived_statement_t<Policies>, Rhs>{}, rhs);
-      }
-
-    private:
-      template <typename Flag, typename Check, typename Rhs>
-      auto _union_impl(Check, Rhs rhs) const -> inconsistent<Check>;
-
-      template <typename Flag, typename Rhs>
-      auto _union_impl(consistent_t /*unused*/, Rhs rhs) const
-          -> _new_statement_t<consistent_t, union_t<Flag, derived_statement_t<Policies>, Rhs>>
-      {
-        return {blank_union_t{}, union_data_t<Flag, derived_statement_t<Policies>, Rhs>{
-                                     static_cast<const derived_statement_t<Policies>&>(*this), rhs}};
-      }
-    };
-  };
-
-  /*
-  template <typename T>
-  auto union_all(T&& t) -> decltype(statement_t<no_union_t>().union_all(std::forward<T>(t)))
-  {
-    return statement_t<no_union_t>().union_all(std::forward<T>(t));
-  }
-
-  template <typename T>
-  auto union_distinct(T&& t) -> decltype(statement_t<no_union_t>().union_distinct(std::forward<T>(t)))
-  {
-    return statement_t<no_union_t>().union_distinct(std::forward<T>(t));
-  }
-  */
-}  // namespace sqlpp
diff --git a/include/sqlpp11/upper.h b/include/sqlpp11/upper.h
deleted file mode 100644
index 466e739b..00000000
--- a/include/sqlpp11/upper.h
+++ /dev/null
@@ -1,72 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2023, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/serialize.h>
-#include <sqlpp11/type_traits.h>
-
-namespace sqlpp
-{
-  template <typename Expr>
-  struct upper_t
-  {
-    using _traits = make_traits<text, tag::is_expression, tag::is_selectable>;
-
-    using _nodes = detail::type_vector<Expr>;
-
-    upper_t(const Expr expr) : _expr(expr)
-    {
-    }
-
-    upper_t(const upper_t&) = default;
-    upper_t(upper_t&&) = default;
-    upper_t& operator=(const upper_t&) = default;
-    upper_t& operator=(upper_t&&) = default;
-    ~upper_t() = default;
-
-    Expr _expr;
-  };
-
-  template <typename Context, typename Expr>
-  Context& serialize(Context& context, const upper_t<Expr>& t)
-  {
-    context << "UPPER(";
-    serialize_operand(context, t._expr);
-    context << ")";
-    return context;
-  }
-
-  template<typename T>
-    using check_upper_args = std::enable_if_t<is_text<T>::value>;
-
-  template <typename T, typename = check_upper_args<T>>
-  auto upper(T t) -> upper_t<T>
-  {
-    return {std::move(t)};
-  }
-
-}  // namespace sqlpp
diff --git a/include/sqlpp11/without_table_check.h b/include/sqlpp11/without_table_check.h
deleted file mode 100644
index 793d83b4..00000000
--- a/include/sqlpp11/without_table_check.h
+++ /dev/null
@@ -1,60 +0,0 @@
-#pragma once
-
-/*
- * Copyright (c) 2016-2016, Roland Bock
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- *   Redistributions of source code must retain the above copyright notice, this
- *   list of conditions and the following disclaimer.
- *
- *   Redistributions in binary form must reproduce the above copyright notice, this
- *   list of conditions and the following disclaimer in the documentation and/or
- *   other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
- * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include <sqlpp11/type_traits.h>
-
-namespace sqlpp
-{
-  template <typename Expression>
-  struct without_table_check_t: public Expression
-  {
-    using _required_tables = detail::type_set<>;
-
-    without_table_check_t(Expression expression) : Expression(expression)
-    {
-    }
-
-    const Expression& expr() const { return *this; }
-  };
-
-  template <typename Context, typename Expression>
-  Context& serialize(Context& context, const without_table_check_t<Expression>& t)
-  {
-    serialize(context, t.expr());
-    return context;
-  }
-
-  template <typename Expression>
-  auto without_table_check(Expression expr) -> without_table_check_t<Expression>
-  {
-    static_assert(is_expression_t<Expression>::value or is_alias_t<Expression>::value,
-                  "invalid argument (expression or alias expression expected)");
-
-    return {expr};
-  }
-}  // namespace sqlpp
diff --git a/tests/core/constraints/must_not_insert.cpp b/tests/core/constraints/must_not_insert.cpp
index 7047e7d8..1fffd2cd 100644
--- a/tests/core/constraints/must_not_insert.cpp
+++ b/tests/core/constraints/must_not_insert.cpp
@@ -30,7 +30,7 @@
 
 #include "Sample.h"
 #include "MockDb.h"
-#include <sqlpp11/insert.h>
+#include <sqlpp11/clause/insert.h>
 #include <iostream>
 
 MockDb db;
diff --git a/tests/core/constraints/must_not_update.cpp b/tests/core/constraints/must_not_update.cpp
index 18c9790d..11944091 100644
--- a/tests/core/constraints/must_not_update.cpp
+++ b/tests/core/constraints/must_not_update.cpp
@@ -30,7 +30,7 @@
 
 #include "Sample.h"
 #include "MockDb.h"
-#include <sqlpp11/update.h>
+#include <sqlpp11/clause/update.h>
 
 MockDb db;
 
diff --git a/tests/core/constraints/require_insert.cpp b/tests/core/constraints/require_insert.cpp
index f6e2e405..6c0615de 100644
--- a/tests/core/constraints/require_insert.cpp
+++ b/tests/core/constraints/require_insert.cpp
@@ -30,7 +30,7 @@
 
 #include "Sample.h"
 #include "MockDb.h"
-#include <sqlpp11/insert.h>
+#include <sqlpp11/clause/insert.h>
 #include <iostream>
 
 MockDb db;
diff --git a/tests/core/static_asserts/aggregates.cpp b/tests/core/static_asserts/aggregates.cpp
index 3c1f539d..bc4516cb 100644
--- a/tests/core/static_asserts/aggregates.cpp
+++ b/tests/core/static_asserts/aggregates.cpp
@@ -29,7 +29,7 @@
 #include <sqlpp11/alias_provider.h>
 #include <sqlpp11/connection.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/select.h>
 
 namespace
 {
diff --git a/tests/core/types/CMakeLists.txt b/tests/core/types/CMakeLists.txt
index 73f12ce1..e260ba8c 100644
--- a/tests/core/types/CMakeLists.txt
+++ b/tests/core/types/CMakeLists.txt
@@ -35,7 +35,7 @@ function(test_compile name)
 endfunction()
 
 add_subdirectory(operator)
-test_compile(aggregate_functions)
+test_compile(aggregate_function)
 test_compile(case_when)
 test_compile(dynamic)
 test_compile(result_row)
diff --git a/tests/core/types/aggregate_functions.cpp b/tests/core/types/aggregate_function.cpp
similarity index 100%
rename from tests/core/types/aggregate_functions.cpp
rename to tests/core/types/aggregate_function.cpp
diff --git a/tests/core/types/dynamic.cpp b/tests/core/types/dynamic.cpp
index bd87fd6b..ccd4b255 100644
--- a/tests/core/types/dynamic.cpp
+++ b/tests/core/types/dynamic.cpp
@@ -56,8 +56,8 @@ void test_dynamic(Value v)
 
   static_assert(not sqlpp::has_name<decltype(v_not_null)>::value, "");
   static_assert(not sqlpp::has_name<decltype(v_maybe_null)>::value, "");
-  static_assert(sqlpp::has_name<decltype(v_not_null_alias)>::value, "");
-  static_assert(sqlpp::has_name<decltype(v_maybe_null_alias)>::value, "");
+  static_assert(not sqlpp::has_name<decltype(v_not_null_alias)>::value, "");
+  static_assert(not sqlpp::has_name<decltype(v_maybe_null_alias)>::value, "");
 
   static_assert(is_select_column_value_type<decltype(v_not_null), OptValueType>::value, "");
   static_assert(is_select_column_value_type<decltype(v_maybe_null), OptValueType>::value, "");
diff --git a/tests/core/types/select_as.cpp b/tests/core/types/select_as.cpp
index c7f5b958..173d51da 100644
--- a/tests/core/types/select_as.cpp
+++ b/tests/core/types/select_as.cpp
@@ -76,8 +76,11 @@ void test_select_as(Value v)
   static_assert(is_same_type<decltype(select(v_maybe_null).as(column).sometimes), OptValueType>(), "");
 
   // The column of a single-value pseudo table can be renamed and used as named value
-  static_assert(sqlpp::has_name<decltype(select(v_not_null).as(column).always.as(foo))>::value, "");
-  static_assert(sqlpp::has_name<decltype(select(v_maybe_null).as(column).sometimes.as(foo))>::value, "");
+  static_assert(not sqlpp::has_name<decltype(select(v_not_null).as(column).always.as(foo))>::value, "");
+  static_assert(not sqlpp::has_name<decltype(select(v_maybe_null).as(column).sometimes.as(foo))>::value, "");
+
+  static_assert(sqlpp::select_column_has_name<decltype(select(v_not_null).as(column).always.as(foo))>::value, "");
+  static_assert(sqlpp::select_column_has_name<decltype(select(v_maybe_null).as(column).sometimes.as(foo))>::value, "");
 
   static_assert(is_select_column_same_type<decltype(select(v_not_null).as(column).always.as(foo)), ValueType>(), "");
   static_assert(is_select_column_same_type<decltype(select(v_maybe_null).as(column).sometimes.as(foo)), OptValueType>(), "");
@@ -102,8 +105,11 @@ void test_select_as(Value v)
   static_assert(is_same_type<decltype(select(v_not_null, v_maybe_null).as(table).sometimes), OptValueType>(), "");
 
   // The column of a multi-value pseudo table can be renamed and used as named value
-  static_assert(sqlpp::has_name<decltype(select(v_not_null, v_maybe_null).as(table).always.as(foo))>::value, "");
-  static_assert(sqlpp::has_name<decltype(select(v_not_null, v_maybe_null).as(table).sometimes.as(foo))>::value, "");
+  static_assert(not sqlpp::has_name<decltype(select(v_not_null, v_maybe_null).as(table).always.as(foo))>::value, "");
+  static_assert(not sqlpp::has_name<decltype(select(v_not_null, v_maybe_null).as(table).sometimes.as(foo))>::value, "");
+
+  static_assert(sqlpp::select_column_has_name<decltype(select(v_not_null, v_maybe_null).as(table).always.as(foo))>::value, "");
+  static_assert(sqlpp::select_column_has_name<decltype(select(v_not_null, v_maybe_null).as(table).sometimes.as(foo))>::value, "");
 
   static_assert(is_select_column_same_type<decltype(select(v_not_null, v_maybe_null).as(table).always.as(foo)), ValueType>(), "");
   static_assert(is_select_column_same_type<decltype(select(v_not_null, v_maybe_null).as(table).sometimes.as(foo)), OptValueType>(), "");
diff --git a/tests/core/usage/Function.cpp b/tests/core/usage/Function.cpp
index eb1cbdb7..a2ed0839 100644
--- a/tests/core/usage/Function.cpp
+++ b/tests/core/usage/Function.cpp
@@ -27,7 +27,7 @@
 #include "MockDb.h"
 #include <sqlpp11/auto_alias.h>
 #include <sqlpp11/alias_provider.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/select.h>
 #include <sqlpp11/functions.h>
 #include <sqlpp11/connection.h>
 
diff --git a/tests/core/usage/Insert.cpp b/tests/core/usage/Insert.cpp
index 36a48621..1014406b 100644
--- a/tests/core/usage/Insert.cpp
+++ b/tests/core/usage/Insert.cpp
@@ -29,8 +29,8 @@
 #include <iostream>
 #include <sqlpp11/compat/string_view.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/insert.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/insert.h>
+#include <sqlpp11/clause/select.h>
 
 int Insert(int, char*[])
 {
diff --git a/tests/core/usage/Prepared.cpp b/tests/core/usage/Prepared.cpp
index eb4ae271..3faddda1 100644
--- a/tests/core/usage/Prepared.cpp
+++ b/tests/core/usage/Prepared.cpp
@@ -27,7 +27,7 @@
 #include "MockDb.h"
 #include "is_regular.h"
 #include <sqlpp11/functions.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/select.h>
 #include "../../include/test_helpers.h"
 
 int Prepared(int, char* [])
diff --git a/tests/core/usage/Select.cpp b/tests/core/usage/Select.cpp
index ac166b79..dfbf76ed 100644
--- a/tests/core/usage/Select.cpp
+++ b/tests/core/usage/Select.cpp
@@ -31,8 +31,7 @@
 #include <sqlpp11/alias_provider.h>
 #include <sqlpp11/connection.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/select.h>
-#include <sqlpp11/without_table_check.h>
+#include <sqlpp11/clause/select.h>
 #include "../../include/test_helpers.h"
 
 struct to_cerr
diff --git a/tests/core/usage/SelectType.cpp b/tests/core/usage/SelectType.cpp
index fa4d8cfa..3adf8262 100644
--- a/tests/core/usage/SelectType.cpp
+++ b/tests/core/usage/SelectType.cpp
@@ -29,8 +29,7 @@
 #include <sqlpp11/alias_provider.h>
 #include <sqlpp11/connection.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/select.h>
-#include <sqlpp11/without_table_check.h>
+#include <sqlpp11/clause/select.h>
 #include "../../include/test_helpers.h"
 
 namespace alias
diff --git a/tests/core/usage/Union.cpp b/tests/core/usage/Union.cpp
index fca49f70..aab7ffd2 100644
--- a/tests/core/usage/Union.cpp
+++ b/tests/core/usage/Union.cpp
@@ -25,7 +25,7 @@
 
 #include "Sample.h"
 #include "MockDb.h"
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/select.h>
 #include <sqlpp11/alias_provider.h>
 #include <iostream>
 
diff --git a/tests/core/usage/With.cpp b/tests/core/usage/With.cpp
index cf136cd9..09239eba 100644
--- a/tests/core/usage/With.cpp
+++ b/tests/core/usage/With.cpp
@@ -25,7 +25,7 @@
 
 #include "Sample.h"
 #include "MockDb.h"
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/select.h>
 #include <sqlpp11/alias_provider.h>
 #include <iostream>
 #include "../../include/test_helpers.h"
diff --git a/tests/include/ConnectionPoolTests.h b/tests/include/ConnectionPoolTests.h
index 0db71d87..821eff39 100644
--- a/tests/include/ConnectionPoolTests.h
+++ b/tests/include/ConnectionPoolTests.h
@@ -60,7 +60,7 @@ namespace sqlpp
         }
         for (;;) {
           auto handle = pool.get().native_handle();
-          auto insert_res = ns.insert(handle);
+          auto insert_res = ns.clause/insert.handle);
           if (insert_res.second == false) {
             return ns;
           }
diff --git a/tests/mysql/usage/DynamicSelect.cpp b/tests/mysql/usage/DynamicSelect.cpp
index 9f98ec95..9750463e 100644
--- a/tests/mysql/usage/DynamicSelect.cpp
+++ b/tests/mysql/usage/DynamicSelect.cpp
@@ -27,12 +27,12 @@
 #include "Tables.h"
 #include <sqlpp11/alias_provider.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/insert.h>
+#include <sqlpp11/clause/insert.h>
 #include <sqlpp11/mysql/connection.h>
-#include <sqlpp11/remove.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/remove.h>
+#include <sqlpp11/clause/select.h>
 #include <sqlpp11/transaction.h>
-#include <sqlpp11/update.h>
+#include <sqlpp11/clause/update.h>
 
 #include <iostream>
 #include <vector>
diff --git a/tests/mysql/usage/MoveConstructor.cpp b/tests/mysql/usage/MoveConstructor.cpp
index 0a839ff7..bc7ff895 100644
--- a/tests/mysql/usage/MoveConstructor.cpp
+++ b/tests/mysql/usage/MoveConstructor.cpp
@@ -27,12 +27,12 @@
 #include "Tables.h"
 #include <sqlpp11/alias_provider.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/insert.h>
+#include <sqlpp11/clause/insert.h>
 #include <sqlpp11/mysql/connection.h>
-#include <sqlpp11/remove.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/remove.h>
+#include <sqlpp11/clause/select.h>
 #include <sqlpp11/transaction.h>
-#include <sqlpp11/update.h>
+#include <sqlpp11/clause/update.h>
 
 #include <cassert>
 #include <iostream>
diff --git a/tests/mysql/usage/Prepared.cpp b/tests/mysql/usage/Prepared.cpp
index bf72b7a1..fb220f42 100644
--- a/tests/mysql/usage/Prepared.cpp
+++ b/tests/mysql/usage/Prepared.cpp
@@ -28,12 +28,12 @@
 #include <cassert>
 #include <sqlpp11/alias_provider.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/insert.h>
+#include <sqlpp11/clause/insert.h>
 #include <sqlpp11/mysql/connection.h>
-#include <sqlpp11/remove.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/remove.h>
+#include <sqlpp11/clause/select.h>
 #include <sqlpp11/transaction.h>
-#include <sqlpp11/update.h>
+#include <sqlpp11/clause/update.h>
 
 #include <iostream>
 #include <vector>
diff --git a/tests/mysql/usage/Select.cpp b/tests/mysql/usage/Select.cpp
index 1f7024dc..8d5223e4 100644
--- a/tests/mysql/usage/Select.cpp
+++ b/tests/mysql/usage/Select.cpp
@@ -28,12 +28,12 @@
 #include <cassert>
 #include <sqlpp11/alias_provider.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/insert.h>
+#include <sqlpp11/clause/insert.h>
 #include <sqlpp11/mysql/connection.h>
-#include <sqlpp11/remove.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/remove.h>
+#include <sqlpp11/clause/select.h>
 #include <sqlpp11/transaction.h>
-#include <sqlpp11/update.h>
+#include <sqlpp11/clause/update.h>
 #include "../../include/test_helpers.h"
 
 #include <iostream>
diff --git a/tests/mysql/usage/Truncated.cpp b/tests/mysql/usage/Truncated.cpp
index 713893ae..16ceb84a 100644
--- a/tests/mysql/usage/Truncated.cpp
+++ b/tests/mysql/usage/Truncated.cpp
@@ -28,12 +28,12 @@
 #include <cassert>
 #include <sqlpp11/alias_provider.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/insert.h>
+#include <sqlpp11/clause/insert.h>
 #include <sqlpp11/mysql/connection.h>
-#include <sqlpp11/remove.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/remove.h>
+#include <sqlpp11/clause/select.h>
 #include <sqlpp11/transaction.h>
-#include <sqlpp11/update.h>
+#include <sqlpp11/clause/update.h>
 #include "../../include/test_helpers.h"
 
 #include <iostream>
diff --git a/tests/sqlite3/usage/DynamicLoadingTest.cpp b/tests/sqlite3/usage/DynamicLoadingTest.cpp
index 439b8c66..15c45ac2 100644
--- a/tests/sqlite3/usage/DynamicLoadingTest.cpp
+++ b/tests/sqlite3/usage/DynamicLoadingTest.cpp
@@ -26,12 +26,12 @@
 #include "TabSample.h"
 #include <sqlpp11/alias_provider.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/insert.h>
-#include <sqlpp11/remove.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/insert.h>
+#include <sqlpp11/clause/remove.h>
+#include <sqlpp11/clause/select.h>
 #include <sqlpp11/sqlite3/connection.h>
 #include <sqlpp11/transaction.h>
-#include <sqlpp11/update.h>
+#include <sqlpp11/clause/update.h>
 
 #ifdef SQLPP_USE_SQLCIPHER
 #include <sqlcipher/sqlite3.h>
diff --git a/tests/sqlite3/usage/DynamicSelect.cpp b/tests/sqlite3/usage/DynamicSelect.cpp
index 0078d216..16caa8a1 100644
--- a/tests/sqlite3/usage/DynamicSelect.cpp
+++ b/tests/sqlite3/usage/DynamicSelect.cpp
@@ -26,12 +26,12 @@
 #include "Tables.h"
 #include <sqlpp11/alias_provider.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/insert.h>
-#include <sqlpp11/remove.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/insert.h>
+#include <sqlpp11/clause/remove.h>
+#include <sqlpp11/clause/select.h>
 #include <sqlpp11/sqlite3/connection.h>
 #include <sqlpp11/transaction.h>
-#include <sqlpp11/update.h>
+#include <sqlpp11/clause/update.h>
 
 #ifdef SQLPP_USE_SQLCIPHER
 #include <sqlcipher/sqlite3.h>
diff --git a/tests/sqlite3/usage/Select.cpp b/tests/sqlite3/usage/Select.cpp
index f01e97d5..6daf1262 100644
--- a/tests/sqlite3/usage/Select.cpp
+++ b/tests/sqlite3/usage/Select.cpp
@@ -28,12 +28,12 @@
 #include <cassert>
 #include <sqlpp11/alias_provider.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/insert.h>
-#include <sqlpp11/remove.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/insert.h>
+#include <sqlpp11/clause/remove.h>
+#include <sqlpp11/clause/select.h>
 #include <sqlpp11/sqlite3/connection.h>
 #include <sqlpp11/transaction.h>
-#include <sqlpp11/update.h>
+#include <sqlpp11/clause/update.h>
 
 #include <iostream>
 #include <vector>
diff --git a/tests/sqlite3/usage/Transaction.cpp b/tests/sqlite3/usage/Transaction.cpp
index 2090bd96..c444f80e 100644
--- a/tests/sqlite3/usage/Transaction.cpp
+++ b/tests/sqlite3/usage/Transaction.cpp
@@ -27,12 +27,12 @@
 #include <sqlpp11/alias_provider.h>
 #include <sqlpp11/custom_query.h>
 #include <sqlpp11/functions.h>
-#include <sqlpp11/insert.h>
-#include <sqlpp11/remove.h>
-#include <sqlpp11/select.h>
+#include <sqlpp11/clause/insert.h>
+#include <sqlpp11/clause/remove.h>
+#include <sqlpp11/clause/select.h>
 #include <sqlpp11/sqlite3/connection.h>
 #include <sqlpp11/transaction.h>
-#include <sqlpp11/update.h>
+#include <sqlpp11/clause/update.h>
 
 #ifdef SQLPP_USE_SQLCIPHER
 #include <sqlcipher/sqlite3.h>