diff --git a/include/sqlpp11/core/basic/table.h b/include/sqlpp11/core/basic/table.h
index f81b58d0..51397441 100644
--- a/include/sqlpp11/core/basic/table.h
+++ b/include/sqlpp11/core/basic/table.h
@@ -75,11 +75,6 @@ namespace sqlpp
   {
   };
 
-  template <typename TableSpec>
-  struct provided_optional_tables_of<table_t<TableSpec>> : public provided_tables_of<table_t<TableSpec>>
-  {
-  };
-
   template <typename Context, typename TableSpec>
   auto to_sql_string(Context& context, const table_t<TableSpec>& /*unused*/) -> std::string
   {
diff --git a/include/sqlpp11/core/clause/single_table.h b/include/sqlpp11/core/clause/single_table.h
index 675da1b6..f795f2cd 100644
--- a/include/sqlpp11/core/clause/single_table.h
+++ b/include/sqlpp11/core/clause/single_table.h
@@ -90,7 +90,7 @@ namespace sqlpp
   template <typename Table>
   struct check_update_table
   {
-    using type = static_combined_check_t<static_check_t<is_table<Table>::value, assert_update_table_arg_is_table_t>>;
+    using type = static_combined_check_t<static_check_t<is_raw_table<Table>::value, assert_update_table_arg_is_table_t>>;
   };
   template <typename Table>
   using check_update_table_t = typename check_update_table<Table>::type;
@@ -147,4 +147,10 @@ namespace sqlpp
   {
     return to_sql_string(context, t._table);
   }
+
+  template <typename T>
+  auto single_table(T&& t) -> decltype(statement_t<no_single_table_t>().single_table(std::forward<T>(t)))
+  {
+    return statement_t<no_single_table_t>().single_table(std::forward<T>(t));
+  }
 }  // namespace sqlpp
diff --git a/include/sqlpp11/core/type_traits/aggregates.h b/include/sqlpp11/core/type_traits/aggregates.h
index fa84a1ce..f8238310 100644
--- a/include/sqlpp11/core/type_traits/aggregates.h
+++ b/include/sqlpp11/core/type_traits/aggregates.h
@@ -76,7 +76,7 @@ namespace sqlpp
   struct is_aggregate_expression
       : public std::integral_constant<bool,
                                       is_aggregate_function<T>::value or
-                                          KnownAggregateColumns::template contains<T>::value>
+                                          KnownAggregateColumns::template contains<T>()>
   {
   };
 
diff --git a/tests/core/types/CMakeLists.txt b/tests/core/types/CMakeLists.txt
index 1e8392f5..9f737c4c 100644
--- a/tests/core/types/CMakeLists.txt
+++ b/tests/core/types/CMakeLists.txt
@@ -33,4 +33,10 @@ test_compile(result_row)
 test_compile(select_as)
 test_compile(value)
 
+add_subdirectory(aggregate_function)
 add_subdirectory(basic)
+add_subdirectory(clause)
+add_subdirectory(detail)
+add_subdirectory(operator)
+add_subdirectory(type_traits)
+
diff --git a/tests/core/types/basic/join.cpp b/tests/core/types/basic/join.cpp
index c74b745e..98fd219f 100644
--- a/tests/core/types/basic/join.cpp
+++ b/tests/core/types/basic/join.cpp
@@ -152,6 +152,7 @@ void test_group_by()
 
 
 #warning: Need to add tests with verbatim tables
+#warning: Need to add tests with schema qualified tables
 #warning: Need to add tests with 3 tables
 
 #warning: Need to add tests with CTEs
diff --git a/tests/core/types/basic/table.cpp b/tests/core/types/basic/table.cpp
index d448ae96..5d5d35f6 100644
--- a/tests/core/types/basic/table.cpp
+++ b/tests/core/types/basic/table.cpp
@@ -37,7 +37,8 @@ void test_table()
   static_assert(std::is_same<sqlpp::name_tag_of_t<test::TabFoo>, test::TabFoo_::_sqlpp_name_tag>::value, "");
   static_assert(std::is_same<sqlpp::provided_tables_of_t<test::TabFoo>, sqlpp::detail::type_vector<test::TabFoo>>::value, "");
   static_assert(std::is_same<sqlpp::provided_static_tables_of_t<test::TabFoo>, sqlpp::provided_tables_of_t<test::TabFoo>>::value, "");
-  static_assert(std::is_same<sqlpp::provided_optional_tables_of_t<test::TabFoo>, sqlpp::provided_tables_of_t<test::TabFoo>>::value, "");
+  // Only joins can provide optional tables.
+  static_assert(std::is_same<sqlpp::provided_optional_tables_of_t<test::TabFoo>, sqlpp::detail::type_vector<>>::value, "");
 }
 
 int main()
diff --git a/tests/core/types/clause/CMakeLists.txt b/tests/core/types/clause/CMakeLists.txt
index a895c99c..1bd41fe8 100644
--- a/tests/core/types/clause/CMakeLists.txt
+++ b/tests/core/types/clause/CMakeLists.txt
@@ -29,5 +29,7 @@ function(test_compile name)
 endfunction()
 
 test_compile(group_by)
+test_compile(into)
 test_compile(select_columns)
+test_compile(single_table)
 
diff --git a/tests/core/types/clause/into.cpp b/tests/core/types/clause/into.cpp
new file mode 100644
index 00000000..1181f1dd
--- /dev/null
+++ b/tests/core/types/clause/into.cpp
@@ -0,0 +1,63 @@
+/*
+ * 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 "Sample.h"
+#include <sqlpp11/sqlpp11.h>
+
+SQLPP_CREATE_NAME_TAG(cheese);
+
+template <typename T>
+void assert_invalid_argument(T t)
+{
+  using I = decltype(sqlpp::into(t));
+  static_assert(std::is_same<I, sqlpp::assert_into_arg_is_table>::value, "");
+}
+
+void test_into()
+{
+  auto v = sqlpp::value(17);
+  auto foo = test::TabFoo{};
+  auto bar = test::TabBar{};
+  using Foo = decltype(foo);
+  auto id = foo.id;
+
+  // Valid into clause
+  {
+    using I = decltype(sqlpp::into(foo));
+    static_assert(std::is_same<sqlpp::provided_tables_of_t<I>, sqlpp::detail::type_vector<Foo>>::value, "");
+    static_assert(std::is_same<sqlpp::provided_static_tables_of_t<I>, sqlpp::provided_tables_of_t<I>>::value, "");
+    static_assert(std::is_same<sqlpp::provided_optional_tables_of_t<I>, sqlpp::detail::type_vector<>>::value, "");
+  }
+
+  assert_invalid_argument(foo.join(bar));
+  assert_invalid_argument(foo.as(cheese));
+  assert_invalid_argument(id);
+}
+
+int main()
+{
+  void test_into();
+}
+
diff --git a/tests/core/types/clause/single_table.cpp b/tests/core/types/clause/single_table.cpp
new file mode 100644
index 00000000..882c8d84
--- /dev/null
+++ b/tests/core/types/clause/single_table.cpp
@@ -0,0 +1,63 @@
+/*
+ * 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 "Sample.h"
+#include <sqlpp11/sqlpp11.h>
+
+SQLPP_CREATE_NAME_TAG(cheese);
+
+template <typename T>
+void assert_invalid_argument(T t)
+{
+  using S = decltype(sqlpp::single_table(t));
+  static_assert(std::is_same<S, sqlpp::assert_update_table_arg_is_table_t>::value, "");
+}
+
+void test_single_table()
+{
+  auto v = sqlpp::value(17);
+  auto foo = test::TabFoo{};
+  auto bar = test::TabBar{};
+  using Foo = decltype(foo);
+  auto id = foo.id;
+
+  // Valid single table clause
+  {
+    using S = decltype(sqlpp::single_table(foo));
+    static_assert(std::is_same<sqlpp::provided_tables_of_t<S>, sqlpp::detail::type_vector<Foo>>::value, "");
+    static_assert(std::is_same<sqlpp::provided_static_tables_of_t<S>, sqlpp::provided_tables_of_t<S>>::value, "");
+    static_assert(std::is_same<sqlpp::provided_optional_tables_of_t<S>, sqlpp::detail::type_vector<>>::value, "");
+  }
+
+  assert_invalid_argument(foo.join(bar));
+  assert_invalid_argument(foo.as(cheese));
+  assert_invalid_argument(id);
+}
+
+int main()
+{
+  void test_single_table();
+}
+