Rewrite select_as and add type tests

include/sqlpp11/column.h

@@ -67,7 +67,8 @@ namespace sqlpp
     template <typename T = _table>
     auto table() const -> _table
     {
-      static_assert(is_table_t<T>::value, "cannot call get_table for columns of a sub-selects or cte");
+#warning: subselects use pseudo-columns, cte should do the same, I guess?
+      static_assert(is_table<T>::value, "cannot call get_table for columns of a sub-select or cte");
       return _table{};
     }
 

include/sqlpp11/cte.h

@@ -150,7 +150,7 @@ namespace sqlpp
   template <typename AliasProvider, typename Statement, typename... FieldSpecs>
   struct cte_t : public cte_base<AliasProvider, FieldSpecs>::type...
   {
-    using _traits = make_traits<no_value_t, tag::is_cte, tag::is_table>;  // FIXME: is table? really?
+    using _traits = make_traits<no_value_t, tag::is_cte>;
     using _nodes = detail::type_vector<>;
     using _provided_tables = detail::type_set<cte_t>;
     using _required_ctes = detail::make_joined_set_t<required_ctes_of<Statement>, detail::type_set<AliasProvider>>;
@@ -216,8 +216,16 @@ namespace sqlpp
     Statement _statement;
   };
 
-  template<typename AliasProvider, typename Statement, typename... ColumnSpecs>
-    struct name_tag_of<cte_t<AliasProvider, Statement, ColumnSpecs...>> : public name_tag_of<AliasProvider>{};
+#warning: is table? really?
+  template <typename AliasProvider, typename Statement, typename... ColumnSpecs>
+  struct is_table<cte_t<AliasProvider, Statement, ColumnSpecs...>> : public std::true_type
+  {
+  };
+
+  template <typename AliasProvider, typename Statement, typename... ColumnSpecs>
+  struct name_tag_of<cte_t<AliasProvider, Statement, ColumnSpecs...>> : public name_tag_of<AliasProvider>
+  {
+  };
 
   template <typename Context, typename AliasProvider, typename Statement, typename... ColumnSpecs>
   Context& serialize(Context& context, const cte_t<AliasProvider, Statement, ColumnSpecs...>& t)
@@ -235,7 +243,7 @@ namespace sqlpp
   template <typename AliasProvider>
   struct cte_ref_t
   {
-    using _traits = make_traits<no_value_t, tag::is_alias, tag::is_cte, tag::is_table>;  // FIXME: is table? really?
+    using _traits = make_traits<no_value_t, tag::is_alias, tag::is_cte>;
     using _nodes = detail::type_vector<>;
     using _required_ctes = detail::make_type_set_t<AliasProvider>;
     using _provided_tables = detail::type_set<AliasProvider>;
@@ -253,6 +261,10 @@ namespace sqlpp
     }
   };
 
+#warning: is table? really?
+   template<typename AliasProvider>
+    struct is_table<cte_ref_t<AliasProvider>> : public std::true_type{};
+
    template<typename AliasProvider>
     struct name_tag_of<cte_ref_t<AliasProvider>> : public name_tag_of<AliasProvider>{};
 

include/sqlpp11/for_update.h

@@ -98,9 +98,8 @@ namespace sqlpp
     return context;
   }
 
-  template <typename T>
-  auto for_update(T&& t) -> decltype(statement_t<no_for_update_t>().for_update(std::forward<T>(t)))
+  auto for_update() -> decltype(statement_t<no_for_update_t>().for_update())
   {
-    return statement_t<no_for_update_t>().for_update(std::forward<T>(t));
+    return statement_t<no_for_update_t>().for_update();
   }
 }  // namespace sqlpp

include/sqlpp11/from.h

@@ -78,7 +78,7 @@ namespace sqlpp
   {
     using type = static_combined_check_t<
         static_check_t<not is_pre_join_t<Table>::value, assert_from_not_pre_join_t>,
-        static_check_t<is_table_t<Table>::value, assert_from_table_t>,
+        static_check_t<is_table<Table>::value, assert_from_table_t>,
         static_check_t<required_tables_of_t<Table>::size::value == 0, assert_from_dependency_free_t>,
         static_check_t<provided_tables_of<Table>::size::value ==
                            detail::make_name_of_set_t<provided_tables_of<Table>>::size::value,

include/sqlpp11/join.h

@@ -35,7 +35,7 @@ namespace sqlpp
   template <typename PreJoin, typename On>
   struct join_t
   {
-    using _traits = make_traits<no_value_t, tag::is_table, tag::is_join>;
+    using _traits = make_traits<no_value_t, tag::is_join>;
     using _nodes = detail::type_vector<PreJoin, On>;
     using _can_be_null = std::false_type;
     using _provided_tables = provided_tables_of<PreJoin>;
@@ -81,6 +81,9 @@ namespace sqlpp
     On _on;
   };
 
+  template<typename PreJoin, typename On>
+    struct is_table<join_t<PreJoin, On>> : public std::true_type{};
+
   template <typename Context, typename PreJoin, typename On>
   Context& serialize(Context& context, const join_t<PreJoin, On>& t)
   {

include/sqlpp11/parameterized_verbatim.h

@@ -56,6 +56,15 @@ namespace sqlpp
     std::string _verbatim_lhs, _verbatim_rhs;
   };
 
+  template <typename ValueType, typename Expr>
+  struct value_type_of<parameterized_verbatim_t<ValueType, Expr>>
+  {
+    using type = ValueType;
+  };
+
+  template <typename ValueType, typename Expr>
+  struct nodes_of<parameterized_verbatim_t<ValueType, Expr>> : public nodes_of<Expr>{};
+
   template <typename Context, typename ValueType, typename Expr>
   Context& serialize(Context& context, const parameterized_verbatim_t<ValueType, Expr>& t)
   {

include/sqlpp11/pre_join.h

@@ -42,8 +42,8 @@ namespace sqlpp
   struct check_pre_join
   {
     using type = static_combined_check_t<
-        static_check_t<is_table_t<Lhs>::value, assert_pre_join_lhs_table_t>,
-        static_check_t<is_table_t<Rhs>::value, assert_pre_join_rhs_table_t>,
+        static_check_t<is_table<Lhs>::value, assert_pre_join_lhs_table_t>,
+        static_check_t<is_table<Rhs>::value, assert_pre_join_rhs_table_t>,
         static_check_t<not is_join_t<Rhs>::value, assert_pre_join_rhs_no_join_t>,
         static_check_t<detail::is_disjunct_from<detail::make_name_of_set_t<provided_tables_of<Lhs>>,
                                                 detail::make_name_of_set_t<provided_tables_of<Rhs>>>::value,
@@ -93,8 +93,8 @@ namespace sqlpp
     using _can_be_null = std::false_type;
     using _provided_outer_tables = typename JoinType::template _provided_outer_tables<Lhs, Rhs>;
 
-    static_assert(is_table_t<Lhs>::value, "lhs argument for join() has to be a table or join");
-    static_assert(is_table_t<Rhs>::value, "rhs argument for join() has to be a table");
+    static_assert(is_table<Lhs>::value, "lhs argument for join() has to be a table or join");
+    static_assert(is_table<Rhs>::value, "rhs argument for join() has to be a table");
     static_assert(not is_join_t<Rhs>::value, "rhs argument for join must not be a join");
 
     static_assert(detail::is_disjunct_from<provided_tables_of<Lhs>, provided_tables_of<Rhs>>::value,

include/sqlpp11/schema_qualified_table.h

@@ -40,7 +40,7 @@ namespace sqlpp
   template <typename Table>
   struct schema_qualified_table_t
   {
-    using _traits = make_traits<value_type_of_t<Table>, tag::is_table>;
+    using _traits = make_traits<value_type_of_t<Table>>;
 
     using _nodes = detail::type_vector<>;
     using _required_ctes = detail::type_set<>;
@@ -61,6 +61,9 @@ namespace sqlpp
     Table _table;
   };
 
+  template<typename Table>
+    struct is_table<schema_qualified_table_t<Table>> : public std::true_type {};
+
   template <typename Context, typename Table>
   Context& serialize(Context& context, const schema_qualified_table_t<Table>& t)
   {

include/sqlpp11/select_as.h

@@ -0,0 +1,92 @@
+#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/type_traits.h>
+#include <sqlpp11/enable_as.h>
+
+namespace sqlpp
+{
+  // pseudo_column_t is the column of a sub-select used as a table, for instance.
+#warning: Maybe use this for CTE as well
+#warning: Should be in its own header
+  template <typename TableAliasProvider, typename ColumnSpec>
+  struct pseudo_column_t : public enable_as<pseudo_column_t<TableAliasProvider, ColumnSpec>>
+  {
+  };
+  template <typename TableAliasProvider, typename ColumnSpec>
+  struct name_tag_of<pseudo_column_t<TableAliasProvider, ColumnSpec>> : public name_tag_of<ColumnSpec>
+  {
+  };
+
+  template <typename TableAliasProvider, typename ColumnSpec>
+  struct value_type_of<pseudo_column_t<TableAliasProvider, ColumnSpec>> : public value_type_of<ColumnSpec>
+  {
+  };
+
+  template <typename Select, typename AliasProvider, typename... ColumnSpecs>
+  struct select_as_t
+      : public ColumnSpecs::_alias_t::template _member_t<pseudo_column_t<AliasProvider, ColumnSpecs>>...
+  {
+    select_as_t(Select select) : _select(select)
+    {
+    }
+
+    select_as_t(const select_as_t& rhs) = default;
+    select_as_t(select_as_t&& rhs) = default;
+    select_as_t& operator=(const select_as_t& rhs) = default;
+    select_as_t& operator=(select_as_t&& rhs) = default;
+    ~select_as_t() = default;
+
+    Select _select;
+  };
+
+  // The Select expression has a value in case it has just one column selected.
+  template<typename Select, typename AliasProvider, typename ColumnSpec>
+    struct value_type_of<select_as_t<Select, AliasProvider, ColumnSpec>> : value_type_of<Select> {};
+
+  template<typename Select, typename AliasProvider, typename... ColumnSpecs>
+    struct name_tag_of<select_as_t<Select, AliasProvider, ColumnSpecs...>> : name_tag_of<AliasProvider> {};
+
+#warning: Is this (_can_be_used_as_table) required for use as a named value, too?
+  template <typename Select, typename AliasProvider, typename... ColumnSpecs>
+  struct is_table<select_as_t<Select, AliasProvider, ColumnSpecs...>>
+      : std::integral_constant<bool, Select::_can_be_used_as_table()>
+  {
+  };
+
+#warning: V1.0 has empty nodes. Is that correct? In either case document the decision here.
+
+
+  template <typename Context, typename Select, typename AliasProvider, typename... ColumnSpecs>
+  Context& serialize(Context& context, const select_as_t<Select, AliasProvider, ColumnSpecs...>& t)
+  {
+#warning: add AS Alias
+    serialize(context, t._select);
+    return context;
+  }
+}  // namespace sqlpp

include/sqlpp11/select_column_list.h

@@ -32,7 +32,7 @@
 #include <sqlpp11/interpret_tuple.h>
 #include <sqlpp11/policy_update.h>
 #include <sqlpp11/result_row.h>
-#include <sqlpp11/select_pseudo_table.h>
+#include <sqlpp11/select_as.h>
 #include <sqlpp11/table.h>
 #include <tuple>
 
@@ -78,6 +78,22 @@ namespace sqlpp
     };
   }  // namespace detail
 
+  // FIXME: We might use field specs here (same as with cte)
+  //
+  // provide type information for sub-selects that are used as named expressions or tables
+  template <typename Select, typename Column>
+  struct select_column_spec_t: public name_tag_base
+  {
+    using _alias_t = name_tag_of_t<Column>;
+
+#warning: Need to test this!
+    static constexpr bool _depends_on_outer_table =
+        detail::make_intersect_set_t<required_tables_of_t<Column>, typename Select::_used_outer_tables>::size::value >
+        0;
+  };
+  template <typename Select, typename Column>
+    struct value_type_of<select_column_spec_t<Select, Column>> : public value_type_of<Column> {};
+
   SQLPP_PORTABLE_STATIC_ASSERT(
       assert_no_unknown_tables_in_selected_columns_t,
       "at least one selected column requires a table which is otherwise not known in the statement");
@@ -158,25 +174,12 @@ namespace sqlpp
       using _result_row_t = result_row_t<Db, _field_t<Db, Columns>...>;
 
       template <typename AliasProvider>
-      struct _deferred_table_t
-      {
-        using table = select_pseudo_table_t<_statement_t, Columns...>;
-        using alias = typename table::template _alias_t<AliasProvider>;
-      };
-
-      template <typename AliasProvider>
-      using _table_t = typename _deferred_table_t<AliasProvider>::table;
-
-      template <typename AliasProvider>
-      using _alias_t = typename _deferred_table_t<AliasProvider>::alias;
-
-      template <typename AliasProvider>
-      _alias_t<AliasProvider> as(const AliasProvider& aliasProvider) const
+      auto as(const AliasProvider& aliasProvider) const
+          -> select_as_t<_statement_t, AliasProvider, select_column_spec_t<_statement_t, Columns>...>
       {
         consistency_check_t<_statement_t>::verify();
-        static_assert(_statement_t::_can_be_used_as_table(),
-                      "statement cannot be used as table, e.g. due to missing tables");
-        return _table_t<AliasProvider>(_get_statement()).as(aliasProvider);
+        using table = select_as_t<_statement_t, AliasProvider, select_column_spec_t<_statement_t, Columns>...>;
+        return table(_get_statement());
       }
 
       size_t get_no_of_result_columns() const

include/sqlpp11/select_pseudo_table.h

@@ -1,100 +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/type_traits.h>
-#include <sqlpp11/table.h>
-
-namespace sqlpp
-{
-  // FIXME: We might use field specs here (same as with cte)
-  //
-  // provide type information for sub-selects that are used as named expressions or tables
-  template <typename Select, typename NamedExpr>
-  struct select_column_spec_t: public name_tag_base
-  {
-    using _alias_t = name_tag_of_t<NamedExpr>;
-    using has_default = std::false_type;
-
-    static constexpr bool _depends_on_outer_table =
-        detail::make_intersect_set_t<required_tables_of_t<NamedExpr>, typename Select::_used_outer_tables>::size::value >
-        0;
-
-#warning: somehow prevent insert...
-#warning: may need to make value type optional for outer tables
-    using _traits = make_traits<value_type_of_t<NamedExpr>/*,
-                                tag_if<tag::can_be_null, _depends_on_outer_table>*/>;
-  };
-
-  template<typename... NamedExpr>
-  struct select_expression_type {
-    using value_t = no_value_t;
-    static constexpr bool _is_expression = false;
-    static constexpr bool _can_be_null = false;
-  };
-
-  template<typename NamedExpr>
-  struct select_expression_type<NamedExpr> {
-    using value_t = value_type_of_t<NamedExpr>;
-    static constexpr bool _is_expression = true;
-  };
-
-  template <typename Select, typename... NamedExpr>
-  struct select_pseudo_table_t
-      : public table_t<select_pseudo_table_t<Select, NamedExpr...>, select_column_spec_t<Select, NamedExpr>...>
-  {
-    using _expr_t = select_expression_type<NamedExpr...>;
-    using _traits = make_traits<
-        // Usage as named expression
-        typename _expr_t::value_t,
-        tag_if<tag::is_expression, _expr_t::_is_expression>,
-        // Usage as table
-        tag::is_table,
-        tag::is_pseudo_table,
-        tag_if<tag::requires_parens, requires_parens_t<Select>::value>>;
-    using _nodes = detail::type_vector<>;
-
-    select_pseudo_table_t(Select select) : _select(select)
-    {
-    }
-
-    select_pseudo_table_t(const select_pseudo_table_t& rhs) = default;
-    select_pseudo_table_t(select_pseudo_table_t&& rhs) = default;
-    select_pseudo_table_t& operator=(const select_pseudo_table_t& rhs) = default;
-    select_pseudo_table_t& operator=(select_pseudo_table_t&& rhs) = default;
-    ~select_pseudo_table_t() = default;
-
-    Select _select;
-  };
-
-  template <typename Context, typename Select, typename... NamedExpr>
-  Context& serialize(Context& context, const select_pseudo_table_t<Select, NamedExpr...>& t)
-  {
-    serialize(context, t._select);
-    return context;
-  }
-}  // namespace sqlpp

include/sqlpp11/single_table.h

@@ -57,7 +57,8 @@ namespace sqlpp
     using _traits = make_traits<no_value_t, tag::is_single_table>;
     using _nodes = detail::type_vector<Table>;
 
-    static_assert(is_table_t<Table>::value, "argument has to be a table");
+#warning: can't we do this with a table_t<> specialization
+    static_assert(is_table<Table>::value, "argument has to be a table");
     static_assert(required_tables_of_t<Table>::size::value == 0, "table depends on another table");
 
     using _data_t = single_table_data_t<Table>;
@@ -84,7 +85,7 @@ namespace sqlpp
   template <typename Table>
   struct check_update_table
   {
-    using type = static_combined_check_t<static_check_t<is_table_t<Table>::value, assert_update_table_arg_is_table_t>>;
+    using type = static_combined_check_t<static_check_t<is_table<Table>::value, assert_update_table_arg_is_table_t>>;
   };
   template <typename Table>
   using check_update_table_t = typename check_update_table<Table>::type;

include/sqlpp11/table.h

@@ -41,7 +41,7 @@ namespace sqlpp
   template <typename Table, typename... ColumnSpec>
   struct table_t : public ColumnSpec::_alias_t::template _member_t<column_t<Table, ColumnSpec>>...
   {
-    using _traits = make_traits<no_value_t, tag::is_raw_table, tag::is_table>;
+    using _traits = make_traits<no_value_t, tag::is_raw_table>;
 
     using _nodes = detail::type_vector<>;
     using _provided_tables = detail::type_set<Table>;
@@ -102,6 +102,9 @@ namespace sqlpp
   template <typename Table, typename... ColumnSpec>
   struct name_tag_of<table_t<Table, ColumnSpec...>>: public name_tag_of<Table> {};
 
+  template <typename Table, typename... ColumnSpec>
+  struct is_table<table_t<Table, ColumnSpec...>>: public std::true_type {};
+
   template <typename Context, typename Table, typename... ColumnSpec>
   Context& serialize(Context& context, const table_t<Table, ColumnSpec...>& /*unused*/)
   {

include/sqlpp11/table_alias.h

@@ -42,7 +42,6 @@ namespace sqlpp
   struct table_alias_t : public ColumnSpec::_alias_t::template _member_t<column_t<AliasProvider, ColumnSpec>>...
   {
     using _traits = make_traits<value_type_of_t<Table>,
-                                tag::is_table,
                                 tag::is_alias,
                                 tag_if<tag::is_selectable, is_expression_t<Table>::value>>;
 
@@ -97,6 +96,9 @@ namespace sqlpp
     Table _table;
   };
 
+  template<typename AliasProvider, typename Table, typename... ColumnSpec>
+    struct is_table<table_alias_t<AliasProvider, Table, ColumnSpec...>> : public std::true_type{};
+
   template<typename AliasProvider, typename Table, typename... ColumnSpec>
     struct name_tag_of<table_alias_t<AliasProvider, Table, ColumnSpec...>> : public name_tag_of<AliasProvider>{};
 

include/sqlpp11/type_traits.h

@@ -462,7 +462,6 @@ namespace sqlpp
   SQLPP_VALUE_TRAIT_GENERATOR(is_noop)
   SQLPP_VALUE_TRAIT_GENERATOR(is_missing)
   SQLPP_VALUE_TRAIT_GENERATOR(is_return_value)
-  SQLPP_VALUE_TRAIT_GENERATOR(is_table)
   SQLPP_VALUE_TRAIT_GENERATOR(is_raw_table)
   SQLPP_VALUE_TRAIT_GENERATOR(is_pre_join)
   SQLPP_VALUE_TRAIT_GENERATOR(is_join)
@@ -736,6 +735,9 @@ namespace sqlpp
   template<typename T>
   struct has_name : public std::integral_constant<bool, not std::is_same<name_tag_of_t<T>, no_name_t>::value> {};
 
+  template <typename T>
+  struct is_table : public std::false_type{};
+
   template <typename ValueType, typename... Tags>
   struct make_traits
   {

include/sqlpp11/using.h

@@ -79,7 +79,7 @@ namespace sqlpp
   struct check_using
   {
     using type = static_combined_check_t<
-        static_check_t<logic::all_t<is_table_t<Tables>::value...>::value, assert_using_args_are_tables_t>>;
+        static_check_t<logic::all_t<is_table<Tables>::value...>::value, assert_using_args_are_tables_t>>;
   };
   template <typename... Tables>
   using check_using_t = typename check_using<Tables...>::type;

tests/core/serialize/ForUpdate.cpp

@@ -31,6 +31,9 @@ int ForUpdate(int, char* [])
 {
   const auto foo = test::TabFoo{};
 
+  compare(__LINE__, sqlpp::for_update(),
+          " FOR UPDATE ");
+
   compare(__LINE__, select(foo.doubleN).from(foo).unconditionally().for_update(),
           "SELECT tab_foo.double_n FROM tab_foo FOR UPDATE ");
 

tests/core/serialize/SelectAs.cpp

@@ -32,12 +32,25 @@
 SQLPP_ALIAS_PROVIDER(id_count)
 SQLPP_ALIAS_PROVIDER(cheese)
 
+  using namespace sqlpp;
+
 int SelectAs(int, char*[])
 {
   const auto foo = test::TabFoo{};
   const auto bar = test::TabBar{};
 
   // SELECT...AS as selectable column
+  //using S = table_alias_t<cheese_t, select_pseudo_table_t<statement_t<no_with_t, select_t, no_select_flag_list_t, select_column_list_t<as_expression<count_t<noop, column_t<test::TabBar, test::TabBar_::Id> >, id_count_t> >, from_t<test::TabBar>, where_t<unconditional_t>, no_group_by_t, no_having_t, no_order_by_t, no_limit_t, no_offset_t, no_union_t, no_for_update_t>, as_expression<count_t<noop, column_t<test::TabBar, test::TabBar_::Id> >, id_count_t> >, select_column_spec_t<statement_t<no_with_t, select_t, no_select_flag_list_t, select_column_list_t<as_expression<count_t<noop, column_t<test::TabBar, test::TabBar_::Id> >, id_count_t> >, from_t<test::TabBar>, where_t<unconditional_t>, no_group_by_t, no_having_t, no_order_by_t, no_limit_t, no_offset_t, no_union_t, no_for_update_t>, as_expression<count_t<noop, column_t<test::TabBar, test::TabBar_::Id> >, id_count_t> > >;
+  using S = select_pseudo_table_t<statement_t<no_with_t, select_t, no_select_flag_list_t, select_column_list_t<as_expression<count_t<noop, column_t<test::TabBar, test::TabBar_::Id> >, id_count_t> >, from_t<test::TabBar>, where_t<unconditional_t>, no_group_by_t, no_having_t, no_order_by_t, no_limit_t, no_offset_t, no_union_t, no_for_update_t>> ;
+  static_assert(sqlpp::has_value_type<S>::value, "");
+  /*
+  sqlpp::name_tag_of_t<decltype(select(count(bar.id).as(id_count)).from(bar).unconditionally())::_result_type_provider>::hansi;
+  sqlpp::value_type_of_t<decltype(select(count(bar.id).as(id_count)).from(bar).unconditionally())::_result_type_provider>::hansi;
+  static_assert(sqlpp::has_value_type<decltype(select(count(bar.id).as(id_count)).from(bar).unconditionally())>::value, "");
+  static_assert(sqlpp::has_name<decltype(select(count(bar.id).as(id_count)).from(bar).unconditionally())>::value, "");
+  */
+#error: The select itself should not offer an "as" that yields a value.
+#error: The id_count should offer the alias that offers the value.
   compare(__LINE__, select(foo.doubleN, select(count(bar.id).as(id_count)).from(bar).unconditionally().as(cheese)),
           "SELECT tab_foo.double_n,(SELECT COUNT(tab_bar.id) AS id_count FROM tab_bar) AS cheese");
 

tests/core/types/CMakeLists.txt

@@ -42,5 +42,6 @@ test_compile(dynamic)
 test_compile(in_expression)
 test_compile(logical_expression)
 test_compile(result_row)
+test_compile(select_as)
 test_compile(value)
 

tests/core/types/select_as.cpp

@@ -0,0 +1,157 @@
+/*
+ * Copyright (c) 2024, 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 "MockDb.h"
+#include "Sample.h"
+#include <sqlpp11/sqlpp11.h>
+
+namespace
+{
+  auto db = MockDb{};
+
+  template <typename T, typename V>
+  using is_same_type = std::is_same<sqlpp::value_type_of_t<T>, V>;
+}
+
+SQLPP_ALIAS_PROVIDER(always);
+SQLPP_ALIAS_PROVIDER(sometimes);
+SQLPP_ALIAS_PROVIDER(column)
+SQLPP_ALIAS_PROVIDER(table)
+SQLPP_ALIAS_PROVIDER(foo)
+
+template <typename Value>
+void test_select_as(Value v)
+{
+  auto v_not_null = sqlpp::value(v).as(always);
+  auto v_maybe_null = sqlpp::value(sqlpp::compat::make_optional(v)).as(sometimes);
+
+  using ValueType = sqlpp::value_type_of_t<Value>;
+  using OptValueType = sqlpp::value_type_of_t<sqlpp::compat::optional<Value>>;
+
+  // SINGLE VALUE
+
+  // A select of a single value can be used as a value.
+  static_assert(is_same_type<decltype(select(v_not_null)), ValueType>(), "");
+  static_assert(is_same_type<decltype(select(v_maybe_null)), OptValueType>(), "");
+
+  // A select of a single value can be named and used as a named value.
+  static_assert(sqlpp::has_name<decltype(select(v_not_null).as(column))>::value, "");
+  static_assert(sqlpp::has_name<decltype(select(v_maybe_null).as(column))>::value, "");
+
+  static_assert(is_same_type<decltype(select(v_not_null).as(column)), ValueType>(), "");
+  static_assert(is_same_type<decltype(select(v_maybe_null).as(column)), OptValueType>(), "");
+
+  // A select of a single value can be named and used as a pseudo table
+  static_assert(sqlpp::is_table<decltype(select(v_not_null).as(column))>::value, "");
+  static_assert(sqlpp::is_table<decltype(select(v_maybe_null).as(column))>::value, "");
+
+  // The column of a single-value pseudo table can be used as named value
+  static_assert(sqlpp::has_name<decltype(select(v_not_null).as(column).always)>::value, "");
+  static_assert(sqlpp::has_name<decltype(select(v_maybe_null).as(column).sometimes)>::value, "");
+
+  static_assert(is_same_type<decltype(select(v_not_null).as(column).always), ValueType>(), "");
+  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(is_same_type<decltype(select(v_not_null).as(column).always.as(foo)), ValueType>(), "");
+  static_assert(is_same_type<decltype(select(v_maybe_null).as(column).sometimes.as(foo)), OptValueType>(), "");
+
+#warning: implement
+
+  // MULTIPLE VALUES
+#warning: write
+
+  // A select of multiple values can not be used as a value.
+  static_assert(not sqlpp::has_value_type<decltype(select(v_not_null, v_maybe_null))>::value, "");
+
+  // A select of multiple values can be named and used as a named value.
+  static_assert(sqlpp::has_name<decltype(select(v_not_null, v_maybe_null).as(column))>::value, "");
+  static_assert(not sqlpp::has_value_type<decltype(select(v_not_null, v_maybe_null).as(column))>::value, "");
+
+  // A select of multiple values can be named and used as a pseudo table
+  static_assert(sqlpp::is_table<decltype(select(v_not_null, v_maybe_null).as(table))>::value, "");
+
+  // The column of a multi-value pseudo table can be used as named value
+  static_assert(sqlpp::has_name<decltype(select(v_not_null, v_maybe_null).as(table).always)>::value, "");
+  static_assert(sqlpp::has_name<decltype(select(v_not_null, v_maybe_null).as(table).sometimes)>::value, "");
+
+  static_assert(is_same_type<decltype(select(v_not_null, v_maybe_null).as(table).always), ValueType>(), "");
+  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(is_same_type<decltype(select(v_not_null, v_maybe_null).as(table).always.as(foo)), ValueType>(), "");
+  static_assert(is_same_type<decltype(select(v_not_null, v_maybe_null).as(table).sometimes.as(foo)), OptValueType>(), "");
+
+
+}
+
+int main()
+{
+  // boolean
+  test_select_as(bool{true});
+
+  // integral
+  test_select_as(int8_t{7});
+  test_select_as(int16_t{7});
+  test_select_as(int32_t{7});
+  test_select_as(int64_t{7});
+
+  // unsigned integral
+  test_select_as(uint8_t{7});
+  test_select_as(uint16_t{7});
+  test_select_as(uint32_t{7});
+  test_select_as(uint64_t{7});
+
+  // floating point
+  test_select_as(float{7.7});
+  test_select_as(double{7.7});
+
+  // text
+  test_select_as('7');
+  test_select_as("seven");
+  test_select_as(std::string("seven"));
+  test_select_as(sqlpp::compat::string_view("seven"));
+
+  // blob
+  test_select_as(std::vector<uint8_t>{});
+
+  // date
+  test_select_as(::sqlpp::chrono::day_point{});
+
+  // timestamp
+  test_select_as(::sqlpp::chrono::microsecond_point{});
+  using minute_point = std::chrono::time_point<std::chrono::system_clock, std::chrono::minutes>;
+  test_select_as(minute_point{});
+
+  // time_of_day
+  test_select_as(std::chrono::microseconds{});
+}
+

tests/core/usage/Select.cpp

@@ -187,5 +187,12 @@ int Select(int, char*[])
     std::cout << row.doubleN << " " << row.cheese << std::endl;
   }
 
+  // checking #584
+  auto abs = db.prepare(select(t.alpha).from(t).where(sqlpp::parameterized_verbatim<sqlpp::unsigned_integral>(
+                 "ABS(field1 -", sqlpp::parameter(t.alpha), ")") <=
+             sqlpp::parameter(sqlpp::unsigned_integral(), param2)));
+  abs.params.alpha = 7;
+  abs.params.param2 = 7;
+
   return 0;
 }