From 6f056ced8a246f5abbc72d6904e581e4230e24d3 Mon Sep 17 00:00:00 2001
From: rbock <rbock@eudoxos.de>
Date: Thu, 24 Jul 2014 17:36:56 +0200
Subject: [PATCH] Transport can_be_null into subselect used as a result column

---
 include/sqlpp11/select_column_list.h |  1 -
 include/sqlpp11/statement.h          | 12 ++++++++++--
 include/sqlpp11/verbatim_table.h     |  6 +++++-
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/include/sqlpp11/select_column_list.h b/include/sqlpp11/select_column_list.h
index 398cc1e5..0aab60ff 100644
--- a/include/sqlpp11/select_column_list.h
+++ b/include/sqlpp11/select_column_list.h
@@ -54,7 +54,6 @@ namespace sqlpp
 		template<typename Column>
 			struct select_traits<Column>
 			{
-#warning need to transport the "can be null information here"
 				using _traits = make_traits<value_type_of<Column>, tag::select_column_list, tag::return_value, tag::expression, tag::named_expression>;
 				using _name_t = typename Column::_name_t;
 			};
diff --git a/include/sqlpp11/statement.h b/include/sqlpp11/statement.h
index 13e88e64..4d72757b 100644
--- a/include/sqlpp11/statement.h
+++ b/include/sqlpp11/statement.h
@@ -112,7 +112,12 @@ namespace sqlpp
 					using _provided_outer_tables = detail::type_set<>;
 					using _extra_tables = detail::type_set<>;
 					using _parameters = detail::make_parameter_tuple_t<parameters_of<Policies>...>;
-					using _can_be_null = detail::any_t<can_be_null_t<_value_type>::value>;
+					using _can_be_null = detail::any_t<
+									can_be_null_t<_result_type_provider>::value, 
+									::sqlpp::detail::make_intersect_set_t<
+									  required_tables_of<_result_type_provider>, 
+								    provided_outer_tables_of<statement_policies_t>
+								  >::size::value>;
 				};
 			};
 	}
@@ -128,7 +133,10 @@ namespace sqlpp
 	{
 		using _policies_t = typename detail::statement_policies_t<Db, Policies...>;
 
-		using _traits = make_traits<value_type_of<_policies_t>, ::sqlpp::tag::select, tag::expression_if<typename _policies_t::_is_expression>, tag::named_expression_if<typename _policies_t::_is_expression>>;
+		using _traits = make_traits<value_type_of<_policies_t>,
+					::sqlpp::tag::select, 
+					tag::expression_if<typename _policies_t::_is_expression>, 
+					tag::named_expression_if<typename _policies_t::_is_expression>>;
 		using _recursive_traits = typename _policies_t::_recursive_traits;
 		using _used_outer_tables = typename _policies_t::_all_provided_outer_tables;
 
diff --git a/include/sqlpp11/verbatim_table.h b/include/sqlpp11/verbatim_table.h
index 0c7f6576..2e5fa27c 100644
--- a/include/sqlpp11/verbatim_table.h
+++ b/include/sqlpp11/verbatim_table.h
@@ -46,9 +46,13 @@ namespace sqlpp
 		};
 	}
 
-#warning a verbatim table is always an outer table
 	struct verbatim_table_t: public sqlpp::table_t<verbatim_table_t, detail::unusable_pseudo_column_t>
 	{
+		struct _recursive_traits: public sqlpp::table_t<verbatim_table_t, detail::unusable_pseudo_column_t>::_recursive_traits
+		{
+			using _provided_outer_tables = detail::type_set<verbatim_table_t>;
+		};
+
 		struct _name_t {};
 
 		verbatim_table_t(std::string representation):