diff --git a/examples/select.cpp b/examples/select.cpp
index b56ba61b..3bcba136 100644
--- a/examples/select.cpp
+++ b/examples/select.cpp
@@ -34,6 +34,7 @@
 #include "MockDb.h"
 #include <sqlpp11/sqlpp11.h>
 
+SQLPP_ALIAS_PROVIDER(cheesecake);
 
 MockDb db;
 
@@ -42,7 +43,7 @@ test::TabFeature f;
 
 int main()
 {
-	for (const auto& row : db(select(all_of(p)).from(p).where(true)))
+	for (const auto& row : db(select(all_of(p)).from(p).where(p.id > 7)))
 	{
 		int64_t id = row.id;
 		std::string name = row.name;
@@ -51,7 +52,7 @@ int main()
 
 
 #if	0
-	for (const auto& row : db(select(p.name).from(p).where(true)))
+	for (const auto& row : db(select(p.name).from(p).where(p.name.like("Herb%"))))
 	{
 		int64_t id = row.id;
 		std::string name = row.name;
@@ -62,12 +63,12 @@ int main()
 
 
 #if 0
-	for (const auto& row : db(select(p.name, f.name).from(p,f).where(true)))
+	for (const auto& row : db(select(p.name, f.name.as(cheesecake)).from(p,f).where(p.id > 7 and p.feature == 3)))
 	{
 		//int64_t id = row.id;
 		//std::string a = row.a;
 		std::string name = row.name;
-		//int64_t feature = row.feature;
+		std::string feature = row.cheesecake;
 	}
 #endif
 
@@ -90,7 +91,7 @@ int main()
 	
 	
 
-#if 0
+#if !0
 	auto s = select(all_of(p)) 
 				      .from(p, f)
 						  .where(p.name == any(select(f.name)
diff --git a/include/sqlpp11/avg.h b/include/sqlpp11/avg.h
index 4b879ef8..52ae5652 100644
--- a/include/sqlpp11/avg.h
+++ b/include/sqlpp11/avg.h
@@ -37,7 +37,7 @@ namespace sqlpp
 			public alias_operators<avg_t<Flag, Expr>>
 	{
 		using _traits = make_traits<floating_point, tag::is_expression, tag::is_named_expression>;
-		using _recursive_traits = make_recursive_traits<Expr>;
+		using _recursive_traits = make_recursive_traits<Expr, aggregate_function>;
 
 		static_assert(is_noop<Flag>::value or std::is_same<distinct_t, Flag>::value, "avg() used with flag other than 'distinct'");
 		static_assert(is_numeric_t<Expr>::value, "avg() requires a value expression as argument");
@@ -89,6 +89,7 @@ namespace sqlpp
 	template<typename T>
 		auto avg(T t) -> avg_t<noop, wrap_operand_t<T>>
 		{
+			static_assert(not contains_aggregate_function_t<wrap_operand_t<T>>::value, "avg() cannot be used on an aggregate function");
 			static_assert(is_numeric_t<wrap_operand_t<T>>::value, "avg() requires a value expression as argument");
 			return { t };
 		}
@@ -96,6 +97,7 @@ namespace sqlpp
 	template<typename T>
 		auto avg(const distinct_t&, T t) -> avg_t<distinct_t, wrap_operand_t<T>>
 		{
+			static_assert(not contains_aggregate_function_t<wrap_operand_t<T>>::value, "avg() cannot be used on an aggregate function");
 			static_assert(is_numeric_t<wrap_operand_t<T>>::value, "avg() requires a value expression as argument");
 			return { t };
 		}
diff --git a/include/sqlpp11/column.h b/include/sqlpp11/column.h
index 31c9382b..22b5d977 100644
--- a/include/sqlpp11/column.h
+++ b/include/sqlpp11/column.h
@@ -59,7 +59,9 @@ namespace sqlpp
 			using _provided_outer_tables = detail::type_set<>;
 			using _required_tables = detail::type_set<Table>;
 			using _extra_tables = detail::type_set<>;
-			using _can_be_null = column_spec_can_be_null_t<ColumnSpec>;
+			using _tags = typename std::conditional<column_spec_can_be_null_t<ColumnSpec>::value,
+									detail::type_set<tag::can_be_null>,
+									detail::type_set<>>::type;
 		};
 
 		using _spec_t = ColumnSpec;
diff --git a/include/sqlpp11/count.h b/include/sqlpp11/count.h
index 2ed9766d..3dee29ac 100644
--- a/include/sqlpp11/count.h
+++ b/include/sqlpp11/count.h
@@ -38,7 +38,17 @@ namespace sqlpp
 			public alias_operators<count_t<Flag, Expr>>
 	{
 		using _traits = make_traits<integral, tag::is_expression, tag::is_named_expression>;
-		using _recursive_traits = make_recursive_traits<Expr>;
+		struct _recursive_traits
+		{
+			using _required_tables = required_tables_of<Expr>;
+			using _provided_tables = provided_tables_of<Expr>;
+			using _provided_outer_tables = provided_outer_tables_of<Expr>;
+			using _extra_tables = extra_tables_of<Expr>;
+			using _parameters = parameters_of<Expr>;
+			using _tags = detail::make_difference_set_t<detail::joined_set_t<recursive_tags_of<Expr>, recursive_tags_of<aggregate_function>>, 
+						                                      detail::type_set<tag::can_be_null>>;
+		};
+
 
 		static_assert(is_noop<Flag>::value or std::is_same<distinct_t, Flag>::value, "count() used with flag other than 'distinct'");
 		static_assert(is_expression_t<Expr>::value, "count() requires a sql expression as argument");
@@ -90,6 +100,7 @@ namespace sqlpp
 	template<typename T>
 		auto count(T t) -> count_t<noop, wrap_operand_t<T>>
 		{
+			static_assert(not contains_aggregate_function_t<wrap_operand_t<T>>::value, "count() cannot be used on an aggregate function");
 			static_assert(is_expression_t<wrap_operand_t<T>>::value, "count() requires an expression as argument");
 			return { t };
 		}
@@ -97,6 +108,7 @@ namespace sqlpp
 	template<typename T>
 		auto count(const distinct_t&, T t) -> count_t<distinct_t, wrap_operand_t<T>>
 		{
+			static_assert(not contains_aggregate_function_t<wrap_operand_t<T>>::value, "count() cannot be used on an aggregate function");
 			static_assert(is_expression_t<wrap_operand_t<T>>::value, "count() requires an expression as argument");
 			return { t };
 		}
diff --git a/include/sqlpp11/extra_tables.h b/include/sqlpp11/extra_tables.h
index 22623b0d..d2fe8a73 100644
--- a/include/sqlpp11/extra_tables.h
+++ b/include/sqlpp11/extra_tables.h
@@ -59,7 +59,7 @@ namespace sqlpp
 				using _provided_outer_tables = detail::type_set<>;
 				using _provided_tables = detail::type_set<>;
 				using _extra_tables = detail::type_set<Tables...>;
-				using _can_be_null = std::false_type;
+				using _tags = detail::type_set<>;
 			};
 
 			// FIXME: extra_tables must not require tables!
diff --git a/include/sqlpp11/join.h b/include/sqlpp11/join.h
index 30a3db7b..e7b444a7 100644
--- a/include/sqlpp11/join.h
+++ b/include/sqlpp11/join.h
@@ -73,7 +73,7 @@ namespace sqlpp
 				using _provided_outer_tables = typename JoinType::template _provided_outer_tables<Lhs, Rhs>;
 				using _extra_tables = detail::make_joined_set_t<extra_tables_of<Lhs>, extra_tables_of<Rhs>>;
 				using _parameters = detail::make_parameter_tuple_t<parameters_of<Lhs>, parameters_of<Rhs>>;
-				using _can_be_null = std::false_type;
+				using _tags = detail::type_set<>;
 			};
 
 
@@ -94,6 +94,8 @@ namespace sqlpp
 				-> set_on_t<on_t<void, Expr...>>
 				{
 					static_assert(is_noop<On>::value, "cannot call on() twice for a single join()");
+					static_assert(detail::all_t<is_expression_t<Expr>::value...>::value, "at least one argument is not an expression in on()");
+
 					return { _lhs, 
 						_rhs, 
 						{std::tuple<Expr...>{expr...}}
diff --git a/include/sqlpp11/max.h b/include/sqlpp11/max.h
index 8f0f8fb3..95b182a5 100644
--- a/include/sqlpp11/max.h
+++ b/include/sqlpp11/max.h
@@ -37,7 +37,7 @@ namespace sqlpp
 			public alias_operators<max_t<Expr>>
 	{
 		using _traits = make_traits<value_type_of<Expr>, tag::is_expression, tag::is_named_expression>;
-		using _recursive_traits = make_recursive_traits<Expr>;
+		using _recursive_traits = make_recursive_traits<Expr, aggregate_function>;
 
 		static_assert(is_expression_t<Expr>::value, "max() requires a value expression as argument");
 
@@ -83,6 +83,7 @@ namespace sqlpp
 	template<typename T>
 		auto max(T t) -> max_t<wrap_operand_t<T>>
 		{
+			static_assert(not contains_aggregate_function_t<wrap_operand_t<T>>::value, "max() cannot be used on an aggregate function");
 			static_assert(is_expression_t<wrap_operand_t<T>>::value, "max() requires a value expression as argument");
 			return { t };
 		}
diff --git a/include/sqlpp11/min.h b/include/sqlpp11/min.h
index 7846d763..27c923ad 100644
--- a/include/sqlpp11/min.h
+++ b/include/sqlpp11/min.h
@@ -37,7 +37,7 @@ namespace sqlpp
 			public alias_operators<min_t<Expr>>
 	{
 		using _traits = make_traits<value_type_of<Expr>, tag::is_expression, tag::is_named_expression>;
-		using _recursive_traits = make_recursive_traits<Expr>;
+		using _recursive_traits = make_recursive_traits<Expr, aggregate_function>;
 
 		static_assert(is_expression_t<Expr>::value, "min() requires a value expression as argument");
 
@@ -83,6 +83,7 @@ namespace sqlpp
 	template<typename T>
 		auto min(T t) -> min_t<wrap_operand_t<T>>
 		{
+			static_assert(not contains_aggregate_function_t<wrap_operand_t<T>>::value, "min() cannot be used on an aggregate function");
 			static_assert(is_expression_t<wrap_operand_t<T>>::value, "min() requires a value expression as argument");
 			return { t };
 		}
diff --git a/include/sqlpp11/on.h b/include/sqlpp11/on.h
index 945d90ec..2a88eafb 100644
--- a/include/sqlpp11/on.h
+++ b/include/sqlpp11/on.h
@@ -43,7 +43,6 @@ namespace sqlpp
 			using _is_dynamic = is_database<Database>;
 
 			static_assert(_is_dynamic::value or sizeof...(Expr), "at least one expression argument required in on()");
-			static_assert(detail::all_t<is_expression_t<Expr>::value...>::value, "at least one argument is not an expression in on()");
 
 			template<typename E>
 				void add(E expr)
diff --git a/include/sqlpp11/parameter.h b/include/sqlpp11/parameter.h
index a789f56f..38f100c1 100644
--- a/include/sqlpp11/parameter.h
+++ b/include/sqlpp11/parameter.h
@@ -45,7 +45,7 @@ namespace sqlpp
 			using _provided_outer_tables = detail::type_set<>;
 			using _required_tables = detail::type_set<>;
 			using _extra_tables = detail::type_set<>;
-			using _can_be_null = std::true_type;
+			using _tags = detail::type_set<tag::can_be_null>;
 		};
 
 		using _instance_t = member_t<NameType, parameter_value_t<ValueType>>;
diff --git a/include/sqlpp11/result_field_methods.h b/include/sqlpp11/result_field_methods.h
index 54492a38..5829ba91 100644
--- a/include/sqlpp11/result_field_methods.h
+++ b/include/sqlpp11/result_field_methods.h
@@ -88,7 +88,9 @@ namespace sqlpp
 				using _provided_outer_tables = detail::type_set<>;
 				using _required_tables = detail::type_set<>;
 				using _extra_tables = detail::type_set<>;
-				using _can_be_null = column_spec_can_be_null_t<_field_spec_t>;
+				using _tags = typename std::conditional<column_spec_can_be_null_t<_field_spec_t>::value,
+										detail::type_set<tag::can_be_null>,
+										detail::type_set<>>::type;
 			};
 
 		};
diff --git a/include/sqlpp11/statement.h b/include/sqlpp11/statement.h
index e7a3778e..81c376ea 100644
--- a/include/sqlpp11/statement.h
+++ b/include/sqlpp11/statement.h
@@ -98,6 +98,13 @@ namespace sqlpp
 					no_value_t // if a required statement part is missing (e.g. columns in a select), then the statement cannot be used as a value
 						>::type;
 
+				using _can_be_null = detail::any_t<
+					can_be_null_t<_result_type_provider>::value, 
+					detail::make_intersect_set_t<
+						required_tables_of<_result_type_provider>, 
+						_all_provided_outer_tables
+						>::size::value != 0>;
+
 				using _traits = make_traits<_value_type, tag_if<tag::is_expression, not std::is_same<_value_type, no_value_t>::value>>;
 
 				struct _recursive_traits
@@ -107,12 +114,9 @@ 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<_result_type_provider>::value, 
-									detail::make_intersect_set_t<
-									  required_tables_of<_result_type_provider>, 
-								    provided_outer_tables_of<statement_policies_t>
-								  >::size::value != 0>;
+					using _tags = typename std::conditional<_can_be_null::value,
+											detail::type_set<tag::can_be_null>,
+											detail::type_set<>>::type;
 				};
 			};
 	}
diff --git a/include/sqlpp11/sum.h b/include/sqlpp11/sum.h
index 468ac230..0a5679a1 100644
--- a/include/sqlpp11/sum.h
+++ b/include/sqlpp11/sum.h
@@ -37,7 +37,7 @@ namespace sqlpp
 			public alias_operators<sum_t<Flag, Expr>>
 	{
 		using _traits = make_traits<value_type_of<Expr>, tag::is_expression, tag::is_named_expression>;
-		using _recursive_traits = make_recursive_traits<Expr>;
+		using _recursive_traits = make_recursive_traits<Expr, aggregate_function>;
 
 		static_assert(is_noop<Flag>::value or std::is_same<distinct_t, Flag>::value, "sum() used with flag other than 'distinct'");
 		static_assert(is_numeric_t<Expr>::value, "sum() requires a numeric expression as argument");
@@ -89,6 +89,7 @@ namespace sqlpp
 	template<typename T>
 		auto sum(T t) -> sum_t<noop, wrap_operand_t<T>>
 		{
+			static_assert(not contains_aggregate_function_t<wrap_operand_t<T>>::value, "sum() cannot be used on an aggregate function");
 			static_assert(is_numeric_t<wrap_operand_t<T>>::value, "sum() requires a numeric expression as argument");
 			return { t };
 		}
@@ -96,6 +97,7 @@ namespace sqlpp
 	template<typename T>
 		auto sum(const distinct_t&, T t) -> sum_t<distinct_t, wrap_operand_t<T>>
 		{
+			static_assert(not contains_aggregate_function_t<wrap_operand_t<T>>::value, "sum() cannot be used on an aggregate function");
 			static_assert(is_numeric_t<wrap_operand_t<T>>::value, "sum() requires a numeric expression as argument");
 			return { t };
 		}
diff --git a/include/sqlpp11/table.h b/include/sqlpp11/table.h
index 3c370279..a90605be 100644
--- a/include/sqlpp11/table.h
+++ b/include/sqlpp11/table.h
@@ -53,7 +53,7 @@ namespace sqlpp
 			using _provided_tables = detail::type_set<Table>;
 			using _provided_outer_tables = detail::type_set<>;
 			using _extra_tables = detail::type_set<>;
-			using _can_be_null = std::false_type;
+			using _tags = detail::type_set<>;
 		};
 
 		static_assert(sizeof...(ColumnSpec), "at least one column required per table");
diff --git a/include/sqlpp11/table_alias.h b/include/sqlpp11/table_alias.h
index aa95cd83..28425f10 100644
--- a/include/sqlpp11/table_alias.h
+++ b/include/sqlpp11/table_alias.h
@@ -49,7 +49,7 @@ namespace sqlpp
 			using _provided_tables = detail::type_set<AliasProvider>;
 			using _provided_outer_tables = detail::type_set<>;
 			using _extra_tables = detail::type_set<>;
-			using _can_be_null = std::false_type;
+			using _tags = detail::type_set<>;
 		};
 
 		static_assert(required_tables_of<Table>::size::value == 0, "table aliases must not depend on external tables");
diff --git a/include/sqlpp11/type_traits.h b/include/sqlpp11/type_traits.h
index 99d12c22..cfc54987 100644
--- a/include/sqlpp11/type_traits.h
+++ b/include/sqlpp11/type_traits.h
@@ -32,28 +32,40 @@
 
 namespace sqlpp
 {
+	namespace tag
+	{
+		struct can_be_null{};
+		struct contains_aggregate_function{};
+	};
+
 	namespace detail
 	{
 		template<typename T, typename Enable = void>
 		struct can_be_null_impl { using type = std::false_type; };
 		template<typename T>
-		struct can_be_null_impl<T, typename std::enable_if<T::_recursive_traits::_can_be_null::value>::type> { using type = std::true_type; };
+		struct can_be_null_impl<T, typename std::enable_if<is_element_of<tag::can_be_null, typename T::_recursive_traits::_tags>::value>::type> { using type = std::true_type; };
 	}
 	template<typename T>
 	using can_be_null_t = typename detail::can_be_null_impl<T>::type;
 
-	namespace tag\
-	{\
-		struct can_be_null{};\
-	};\
-	namespace detail\
-	{\
-		template<typename T, typename Enable = void>\
-		struct column_spec_can_be_null_impl { using type = std::false_type; };\
-		template<typename T>\
-		struct column_spec_can_be_null_impl<T, typename std::enable_if<detail::is_element_of<tag::can_be_null, typename T::_traits::_tags>::value>::type> { using type = std::true_type; };\
-	}\
-	template<typename T>\
+	namespace detail
+	{
+		template<typename T, typename Enable = void>
+		struct contains_aggregate_function_impl { using type = std::false_type; };
+		template<typename T>
+		struct contains_aggregate_function_impl<T, typename std::enable_if<is_element_of<tag::contains_aggregate_function, typename T::_recursive_traits::_tags>::value>::type> { using type = std::true_type; };
+	}
+	template<typename T>
+	using contains_aggregate_function_t = typename detail::contains_aggregate_function_impl<T>::type;
+
+	namespace detail
+	{
+		template<typename T, typename Enable = void>
+		struct column_spec_can_be_null_impl { using type = std::false_type; };
+		template<typename T>
+		struct column_spec_can_be_null_impl<T, typename std::enable_if<detail::is_element_of<tag::can_be_null, typename T::_traits::_tags>::value>::type> { using type = std::true_type; };
+	}
+	template<typename T>
 	using column_spec_can_be_null_t = typename detail::column_spec_can_be_null_impl<T>::type;
 
 #define SQLPP_VALUE_TRAIT_GENERATOR(name) \
@@ -140,80 +152,35 @@ namespace sqlpp
 
 	namespace detail
 	{
-		template<typename T>
-			struct value_type_of_impl
-			{
-				using type = typename T::_traits::_value_type;
-			};
-
-		template<typename T>
-			struct required_table_of_impl
-			{
-				using type = typename T::_recursive_traits::_required_tables;
-			};
-
-		template<typename T>
-			struct provided_table_of_impl
-			{
-				using type = typename T::_recursive_traits::_provided_tables;
-			};
-
-		template<typename T>
-			struct provided_outer_table_of_impl
-			{
-				using type = typename T::_recursive_traits::_provided_outer_tables;
-			};
-
-		template<typename T>
-			struct extra_table_of_impl
-			{
-				using type = typename T::_recursive_traits::_extra_tables;
-			};
-
-		template<typename T>
-			struct parameters_of_impl
-			{
-				using type = typename T::_recursive_traits::_parameters;
-			};
-
-		template<typename T>
-			struct name_of_impl
-			{
-				using type = typename T::_name_t;
-			};
-
 		template<typename... T>
-			struct make_parameter_tuple_impl
-			{
-				using type = decltype(std::tuple_cat(std::declval<T>()...));
-			};
-
-		template<typename... T>
-			using make_parameter_tuple_t = typename make_parameter_tuple_impl<T...>::type;
+			using make_parameter_tuple_t = decltype(std::tuple_cat(std::declval<T>()...));
 	}
 	template<typename T>
-		using value_type_of = typename detail::value_type_of_impl<T>::type;
+		using value_type_of = typename T::_traits::_value_type;
 
 	template<typename T>
 		using cpp_value_type_of = typename value_type_of<T>::_cpp_value_type;
 
 	template<typename T>
-		using required_tables_of = typename detail::required_table_of_impl<T>::type;
+		using required_tables_of = typename T::_recursive_traits::_required_tables;
 
 	template<typename T>
-		using provided_tables_of = typename detail::provided_table_of_impl<T>::type;
+		using provided_tables_of = typename T::_recursive_traits::_provided_tables;
 
 	template<typename T>
-		using provided_outer_tables_of = typename detail::provided_outer_table_of_impl<T>::type;
+		using provided_outer_tables_of = typename T::_recursive_traits::_provided_outer_tables;
 
 	template<typename T>
-		using extra_tables_of = typename detail::extra_table_of_impl<T>::type;
+		using extra_tables_of = typename T::_recursive_traits::_extra_tables;
 
 	template<typename T>
-		using parameters_of = typename detail::parameters_of_impl<T>::type;
+		using parameters_of = typename T::_recursive_traits::_parameters;
 
 	template<typename T>
-		using name_of = typename detail::name_of_impl<T>::type;
+		using recursive_tags_of = typename T::_recursive_traits::_tags;
+
+	template<typename T>
+		using name_of = typename T::_name_t;
 
 	template<typename ValueType, typename... Tags>
 		struct make_traits
@@ -221,6 +188,7 @@ namespace sqlpp
 			using _value_type = ValueType;
 			using _tags = detail::make_type_set_t<typename ValueType::_tag, Tags...>;
 		};
+
 	template<typename... Arguments>
 		struct make_recursive_traits
 		{
@@ -229,9 +197,26 @@ namespace sqlpp
 			using _provided_outer_tables = detail::make_joined_set_t<provided_outer_tables_of<Arguments>...>;
 			using _extra_tables = detail::make_joined_set_t<extra_tables_of<Arguments>...>;
 			using _parameters = detail::make_parameter_tuple_t<parameters_of<Arguments>...>;
-			using _can_be_null = detail::any_t<can_be_null_t<Arguments>::value...>;
+			using _tags = detail::make_joined_set_t<recursive_tags_of<Arguments>...>;
 		};
 
+	template<typename... Tags>
+		struct recursive_tags
+		{
+			using _required_tables = detail::type_set<>;
+			using _provided_tables = detail::type_set<>;
+			using _provided_outer_tables = detail::type_set<>;
+			using _extra_tables = detail::type_set<>;
+			using _parameters = std::tuple<>;
+			using _tags = detail::type_set<Tags...>;
+		};
+
+	struct aggregate_function
+	{
+		struct _traits { using _value_type = void; using _tags = detail::type_set<>; };
+		using _recursive_traits = recursive_tags<tag::contains_aggregate_function>;
+	};
+
 	template<typename NameProvider, typename Member>
 		using member_t = typename NameProvider::_name_t::template _member_t<Member>;
 
diff --git a/include/sqlpp11/verbatim.h b/include/sqlpp11/verbatim.h
index 0ea6c61a..d1b43006 100644
--- a/include/sqlpp11/verbatim.h
+++ b/include/sqlpp11/verbatim.h
@@ -40,7 +40,7 @@ namespace sqlpp
 		using _traits = make_traits<ValueType, tag::is_expression>;
 		struct _recursive_traits : public make_recursive_traits<>
 		{
-			using _can_be_null = std::true_type; // since we do not know what's going on inside the verbatim, we assume it can be null
+			using _tags = detail::type_set<tag::can_be_null>; // since we do not know what's going on inside the verbatim, we assume it can be null
 		};
 
 		verbatim_t(std::string verbatim): _verbatim(verbatim) {}
diff --git a/test_constraints/CMakeLists.txt b/test_constraints/CMakeLists.txt
index aec592e4..cfa55c46 100644
--- a/test_constraints/CMakeLists.txt
+++ b/test_constraints/CMakeLists.txt
@@ -24,6 +24,7 @@ function(test_constraint name pattern)
 
 endfunction(test_constraint)
 
+test_constraint(count_of_count "cannot be used on an aggregate function")
 test_constraint(no_conversion_operator_if_null_not_trivial "int i = row.alpha")
 test_constraint(require_insert "required column is missing")
 test_constraint(must_not_insert "one assignment is prohibited")
diff --git a/test_constraints/count_of_count.cpp b/test_constraints/count_of_count.cpp
new file mode 100644
index 00000000..95f089db
--- /dev/null
+++ b/test_constraints/count_of_count.cpp
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2013-2014, 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 "Sample.h"
+#include "MockDb.h"
+#include <sqlpp11/functions.h>
+#include <iostream>
+
+MockDb db;
+
+int main()
+{
+	test::TabBar t;
+
+	count(count(t.alpha));
+}