diff --git a/include/sqlpp11/aggregate_functions/max.h b/include/sqlpp11/aggregate_functions/max.h
index b6d72273..7077d06f 100644
--- a/include/sqlpp11/aggregate_functions/max.h
+++ b/include/sqlpp11/aggregate_functions/max.h
@@ -31,40 +31,16 @@
 
 namespace sqlpp
 {
-  struct max_alias_t
-  {
-    struct _alias_t
-    {
-      static constexpr const char _literal[] = "max_";
-      using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
-      template <typename T>
-      struct _member_t
-      {
-        T max;
-        T& operator()()
-        {
-          return max;
-        }
-        const T& operator()() const
-        {
-          return max;
-        }
-      };
-    };
-  };
-
   template <typename Flag, typename Expr>
-  struct max_t : public expression_operators<max_t<Flag, Expr>, value_type_of<Expr>>,
+  struct max_t : public expression_operators<max_t<Flag, Expr>, value_type_of_t<Expr>>,
                  public aggregate_function_operators<max_t<Flag, Expr>>,
                  public alias_operators<max_t<Flag, Expr>>
   {
-    using _traits = make_traits<value_type_of<Expr>, tag::is_expression, tag::is_selectable>;
+    using _traits = make_traits<value_type_of_t<Expr>, tag::is_expression, tag::is_selectable>;
     using _nodes = detail::type_vector<Expr, aggregate_function>;
     using _can_be_null = std::true_type;
     using _is_aggregate_expression = std::true_type;
 
-    using _auto_alias_t = max_alias_t;
-
     max_t(Expr expr) : _expr(expr)
     {
     }
@@ -93,20 +69,18 @@ namespace sqlpp
   }
 
   template <typename T>
-  auto max(T t) -> max_t<noop, wrap_operand_t<T>>
+  using check_max_arg =
+      std::enable_if_t<values_are_comparable<T, T>::value and not contains_aggregate_function_t<T>::value>;
+
+  template <typename T, typename = check_max_arg<T>>
+  auto max(T t) -> max_t<noop, 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 an expression as argument");
-    return {t};
+    return {std::move(t)};
   }
 
-  template <typename T>
-  auto max(const distinct_t& /*unused*/, T t) -> max_t<distinct_t, wrap_operand_t<T>>
+  template <typename T, typename = check_max_arg<T>>
+  auto max(const distinct_t& /*unused*/, T t) -> max_t<distinct_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 an expression as argument");
-    return {t};
+    return {std::move(t)};
   }
 }  // namespace sqlpp
diff --git a/include/sqlpp11/aggregate_functions/min.h b/include/sqlpp11/aggregate_functions/min.h
index d3bb8250..c6432bc1 100644
--- a/include/sqlpp11/aggregate_functions/min.h
+++ b/include/sqlpp11/aggregate_functions/min.h
@@ -54,11 +54,11 @@ namespace sqlpp
   };
 
   template <typename Flag, typename Expr>
-  struct min_t : public expression_operators<min_t<Flag, Expr>, value_type_of<Expr>>,
+  struct min_t : public expression_operators<min_t<Flag, Expr>, value_type_of_t<Expr>>,
                  public aggregate_function_operators<min_t<Flag, Expr>>,
                  public alias_operators<min_t<Flag, Expr>>
   {
-    using _traits = make_traits<value_type_of<Expr>, tag::is_expression, tag::is_selectable>;
+    using _traits = make_traits<value_type_of_t<Expr>, tag::is_expression, tag::is_selectable>;
     using _nodes = detail::type_vector<Expr, aggregate_function>;
     using _can_be_null = std::true_type;
     using _is_aggregate_expression = std::true_type;
diff --git a/include/sqlpp11/aggregate_functions/sum.h b/include/sqlpp11/aggregate_functions/sum.h
index 05f5866e..c299f7f4 100644
--- a/include/sqlpp11/aggregate_functions/sum.h
+++ b/include/sqlpp11/aggregate_functions/sum.h
@@ -54,11 +54,11 @@ namespace sqlpp
   };
 
   template <typename Flag, typename Expr>
-  struct sum_t : public expression_operators<sum_t<Flag, Expr>, value_type_of<Expr>>,
+  struct sum_t : public expression_operators<sum_t<Flag, Expr>, value_type_of_t<Expr>>,
                  public aggregate_function_operators<sum_t<Flag, Expr>>,
                  public alias_operators<sum_t<Flag, Expr>>
   {
-    using _traits = make_traits<value_type_of<Expr>, tag::is_expression, tag::is_selectable>;
+    using _traits = make_traits<value_type_of_t<Expr>, tag::is_expression, tag::is_selectable>;
     using _nodes = detail::type_vector<Expr, aggregate_function>;
     using _can_be_null = std::true_type;
     using _is_aggregate_expression = std::true_type;
diff --git a/include/sqlpp11/alias.h b/include/sqlpp11/alias.h
index 59b19e44..65535596 100644
--- a/include/sqlpp11/alias.h
+++ b/include/sqlpp11/alias.h
@@ -33,11 +33,14 @@ namespace sqlpp
   template <typename Expression, typename AliasProvider>
   struct expression_alias_t
   {
-    using _traits = make_traits<value_type_of<Expression>, tag::is_selectable, tag::is_alias>;
+    using _traits = make_traits<value_type_of_t<Expression>, tag::is_selectable, tag::is_alias>;
     using _nodes = detail::type_vector<Expression>;
 
+#warning Maybe make constructor of expressions private to force construction in the respective functions?
+    /*
     static_assert(is_expression_t<Expression>::value, "invalid argument for an expression alias");
     static_assert(not is_alias_t<Expression>::value, "cannot create an alias of an alias");
+    */
 
     using _alias_t = typename AliasProvider::_alias_t;
 
@@ -59,6 +62,12 @@ namespace sqlpp
     Expression _expression;
   };
 
+  template <typename Expression, typename AliasProvider>
+  struct value_type_of<expression_alias_t<Expression, AliasProvider>>
+  {
+    using type = value_type_of_t<Expression>;
+  };
+
   template <typename Context, typename Expression, typename AliasProvider>
   Context& serialize(const expression_alias_t<Expression, AliasProvider>& t, Context& context)
   {
diff --git a/include/sqlpp11/any.h b/include/sqlpp11/any.h
index e7ee88e8..6aba53fb 100644
--- a/include/sqlpp11/any.h
+++ b/include/sqlpp11/any.h
@@ -35,7 +35,7 @@ namespace sqlpp
   template <typename Select>
   struct any_t
   {
-    using _traits = make_traits<value_type_of<Select>, tag::is_multi_expression>;
+    using _traits = make_traits<value_type_of_t<Select>, tag::is_multi_expression>;
     using _nodes = detail::type_vector<Select>;
 
     any_t(Select select) : _select(select)
diff --git a/include/sqlpp11/arithmetic_expression.h b/include/sqlpp11/arithmetic_expression.h
new file mode 100644
index 00000000..9d44772d
--- /dev/null
+++ b/include/sqlpp11/arithmetic_expression.h
@@ -0,0 +1,107 @@
+#pragma once
+
+/*
+Copyright (c) 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <utility>
+
+#include <sqlpp11/type_traits.h>
+
+namespace sqlpp
+{
+  template <typename L, typename Operator, typename R>
+  struct arithmetic_expression
+  {
+    arithmetic_expression() = delete;
+    constexpr arithmetic_expression(L l, R r) : _l(l), _r(r)
+    {
+    }
+    arithmetic_expression(const arithmetic_expression&) = default;
+    arithmetic_expression(arithmetic_expression&&) = default;
+    arithmetic_expression& operator=(const arithmetic_expression&) = default;
+    arithmetic_expression& operator=(arithmetic_expression&&) = default;
+    ~arithmetic_expression() = default;
+
+    L _l;
+    R _r;
+  };
+
+  template <typename Operator, typename R>
+  struct unary_arithmetic_expression
+  {
+    unary_arithmetic_expression() = delete;
+    constexpr unary_arithmetic_expression(R r) : _r(r)
+    {
+    }
+    unary_arithmetic_expression(const unary_arithmetic_expression&) = default;
+    unary_arithmetic_expression(unary_arithmetic_expression&&) = default;
+    unary_arithmetic_expression& operator=(const unary_arithmetic_expression&) = default;
+    unary_arithmetic_expression& operator=(unary_arithmetic_expression&&) = default;
+    ~unary_arithmetic_expression() = default;
+
+    R _r;
+  };
+
+  template <typename L, typename R>
+  using check_arithmetic_args = std::enable_if_t<has_numeric_value<L>::value and has_numeric_value<R>::value>;
+
+#if 0
+
+  template <typename L, typename Operator, typename R>
+  struct nodes_of<arithmetic_expression<L, Operator, R>>
+  {
+    using type = type_vector<L, R>;
+  };
+
+  template <typename L, typename Operator, typename R>
+  struct value_type_of_t<arithmetic_expression<L, Operator, R>>
+  {
+    using type = numeric_t;
+  };
+
+  template <typename L, typename Operator, typename R>
+  constexpr auto requires_braces_v<arithmetic_expression<L, Operator, R>> = true;
+
+  template <typename Context, typename L, typename Operator, typename R>
+  [[nodiscard]] auto to_sql_string(Context& context, const arithmetic_expression<L, Operator, R>& t)
+  {
+    return to_sql_string(context, embrace(t._l)) + Operator::symbol + to_sql_string(context, embrace(t._r));
+  }
+
+  template <typename Context, typename Operator, typename R>
+  [[nodiscard]] auto to_sql_string(Context& context, const arithmetic_expression<none_t, Operator, R>& t)
+  {
+    return Operator::symbol + to_sql_string(context, embrace(t._r));
+  }
+
+  template <typename Context, typename L1, typename Operator, typename R1, typename R2>
+  [[nodiscard]] auto to_sql_string(Context& context,
+                                   const arithmetic_expression<arithmetic_expression<L1, Operator, R1>, Operator, R2>& t)
+  {
+    return to_sql_string(context, t._l) + Operator::symbol + to_sql_string(context, embrace(t._r));
+  }
+#endif
+}  // namespace sqlpp
diff --git a/include/sqlpp11/basic_expression_operators.h b/include/sqlpp11/basic_expression_operators.h
index 72ae2696..8806566b 100644
--- a/include/sqlpp11/basic_expression_operators.h
+++ b/include/sqlpp11/basic_expression_operators.h
@@ -50,7 +50,7 @@ namespace sqlpp
   using check_comparison_impl = static_combined_check_t<
       static_check_t<logic::any_t<is_expression_t<RhsType>::value, is_multi_expression_t<RhsType>::value>::value,
                      assert_comparison_rhs_is_expression_t>,
-      static_check_t<value_type_of<LhsType>::template _is_valid_operand<RhsType>::value,
+      static_check_t<value_type_of_t<LhsType>::template _is_valid_operand<RhsType>::value,
                      assert_comparison_rhs_is_valid_operand_t>,
       static_check_t<not std::is_same<LhsType, RhsType>::value, assert_comparison_lhs_rhs_differ_t>>;
 
@@ -60,7 +60,7 @@ namespace sqlpp
   template <typename LhsType, typename... RhsType>
   using check_in_impl = static_combined_check_t<
       static_check_t<logic::all_t<is_expression_t<RhsType>::value...>::value, assert_comparison_rhs_is_expression_t>,
-      static_check_t<logic::all_t<value_type_of<LhsType>::template _is_valid_operand<RhsType>::value...>::value,
+      static_check_t<logic::all_t<value_type_of_t<LhsType>::template _is_valid_operand<RhsType>::value...>::value,
                      assert_comparison_rhs_is_valid_operand_t>,
       static_check_t<logic::none_t<std::is_same<LhsType, RhsType>::value...>::value,
                      assert_comparison_lhs_rhs_differ_t>>;
@@ -122,6 +122,7 @@ namespace sqlpp
       using type = in_expression_t<_check, NewExpr, Expr, wrap_operand_t<T>...>;
     };
 
+#if 0
     template <typename T>
     auto operator==(T t) const -> _new_binary_expression_t<equal_to_t, T>
     {
@@ -214,7 +215,9 @@ namespace sqlpp
       check_in_t<Expr, wrap_operand_t<T>...>::verify();
       return {*static_cast<const Expr*>(this), typename wrap_operand<T>::type{t}...};
     }
+#endif
 
+    /*
     template <typename Defer = void>
     auto operator not() const -> return_type_not_t<Expr, Defer>
     {
@@ -229,6 +232,16 @@ namespace sqlpp
       return {*static_cast<const Expr*>(this), wrap_operand_t<R>{r}};
     }
 
+    template <typename R>
+    auto operator or(const R& r) const -> return_type_or_t<Expr, R>
+    {
+      return_type_or<Expr, R>::check::verify();
+      return {*static_cast<const Expr*>(this), wrap_operand_t<R>{r}};
+    }
+
+    */
+
+    /*
     template <typename R>
     auto operator&(const R& r) const -> return_type_bitwise_and_t<Expr, R>
     {
@@ -242,14 +255,9 @@ namespace sqlpp
       return_type_bitwise_or<Expr, R>::check::verify();
       return {*static_cast<const Expr*>(this), wrap_operand_t<R>{r}};
     }
+    */
 
-    template <typename R>
-    auto operator or(const R& r) const -> return_type_or_t<Expr, R>
-    {
-      return_type_or<Expr, R>::check::verify();
-      return {*static_cast<const Expr*>(this), wrap_operand_t<R>{r}};
-    }
-
+    /*
     template <typename R>
     auto operator+(const R& r) const -> return_type_plus_t<Expr, R>
     {
@@ -284,6 +292,7 @@ namespace sqlpp
       return_type_modulus<Expr, R>::check::verify();
       return {*static_cast<const Expr*>(this), wrap_operand_t<R>{r}};
     }
+    */
 
     template <typename Defer = void>
     auto operator+() const -> return_type_unary_plus_t<Expr, Defer>
@@ -292,6 +301,7 @@ namespace sqlpp
       return {*static_cast<const Expr*>(this)};
     }
 
+    /*
     template <typename Defer = void>
     auto operator-() const -> return_type_unary_minus_t<Expr, Defer>
     {
@@ -312,5 +322,6 @@ namespace sqlpp
       return_type_shift_right<Expr, R>::check::verify();
       return {*static_cast<const Expr*>(this), wrap_operand_t<R>{r}};
     }
+    */
   };
 }  // namespace sqlpp
diff --git a/include/sqlpp11/bit_expression.h b/include/sqlpp11/bit_expression.h
new file mode 100644
index 00000000..007ab2c1
--- /dev/null
+++ b/include/sqlpp11/bit_expression.h
@@ -0,0 +1,100 @@
+#pragma once
+
+/*
+Copyright (c) 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <type_traits>
+
+#include <sqlpp11/type_traits.h>
+
+namespace sqlpp
+{
+  template <typename L, typename Operator, typename R>
+  struct bit_expression
+  {
+    bit_expression() = delete;
+    constexpr bit_expression(L l, R r) : _l(l), _r(r)
+    {
+    }
+    bit_expression(const bit_expression&) = default;
+    bit_expression(bit_expression&&) = default;
+    bit_expression& operator=(const bit_expression&) = default;
+    bit_expression& operator=(bit_expression&&) = default;
+    ~bit_expression() = default;
+
+    L _l;
+    R _r;
+  };
+
+  template <typename Operator, typename R>
+  struct unary_bit_expression
+  {
+    unary_bit_expression() = delete;
+    explicit constexpr unary_bit_expression(R r) : _r(r)
+    {
+    }
+    unary_bit_expression(const unary_bit_expression&) = default;
+    unary_bit_expression(unary_bit_expression&&) = default;
+    unary_bit_expression& operator=(const unary_bit_expression&) = default;
+    unary_bit_expression& operator=(unary_bit_expression&&) = default;
+    ~unary_bit_expression() = default;
+
+    R _r;
+  };
+
+  template <typename L, typename R>
+  using check_bit_expression_args = std::enable_if_t<has_integral_value<L>::value and has_integral_value<R>::value>;
+
+#if 0
+  template <typename L, typename Operator, typename R>
+  struct nodes_of<binary_t<L, Operator, R>>
+  {
+    using type = type_vector<L, R>;
+  };
+
+  template <typename L, typename Operator, typename R>
+  struct value_type_of_t<binary_t<L, Operator, R>>
+  {
+    using type = integral_t;
+  };
+
+  template <typename L, typename Operator, typename R>
+  constexpr auto requires_braces_v<binary_t<L, Operator, R>> = true;
+
+  template <typename Context, typename L, typename Operator, typename R>
+  [[nodiscard]] auto to_sql_string(Context& context, const binary_t<L, Operator, R>& t)
+  {
+    return to_sql_string(context, embrace(t._l)) + Operator::symbol + to_sql_string(context, embrace(t._r));
+  }
+
+  template <typename Context, typename Operator, typename R>
+  [[nodiscard]] auto to_sql_string(Context& context, const binary_t<none_t, Operator, R>& t)
+  {
+    return Operator::symbol + to_sql_string(context, embrace(t._r));
+  }
+#endif
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/case.h b/include/sqlpp11/case.h
index d9f83ee2..08a65aec 100644
--- a/include/sqlpp11/case.h
+++ b/include/sqlpp11/case.h
@@ -42,7 +42,7 @@ namespace sqlpp
       static_check_t<is_expression_t<wrap_operand_t<Else>>::value, assert_case_else_expression_t>,
       static_check_t<logic::any_t<is_sql_null_t<Then>::value,
                                   is_sql_null_t<wrap_operand_t<Else>>::value,
-                                  std::is_same<value_type_of<Then>, value_type_of<wrap_operand_t<Else>>>::value>::value,
+                                  std::is_same<value_type_of_t<Then>, value_type_of_t<wrap_operand_t<Else>>>::value>::value,
                      assert_case_then_else_same_type_t>>;
 
   SQLPP_PORTABLE_STATIC_ASSERT(assert_case_then_expression_t, "argument is not a value expression in then()");
@@ -61,10 +61,10 @@ namespace sqlpp
   struct case_t
       : public expression_operators<
             case_t<When, Then, Else>,
-            typename std::conditional<is_sql_null_t<Then>::value, value_type_of<Else>, value_type_of<Then>>::type>,
+            typename std::conditional<is_sql_null_t<Then>::value, value_type_of_t<Else>, value_type_of_t<Then>>::type>,
         public alias_operators<case_t<When, Then, Else>>
   {
-    using _traits = make_traits<value_type_of<Then>, tag::is_expression>;
+    using _traits = make_traits<value_type_of_t<Then>, tag::is_expression>;
     using _nodes = detail::type_vector<When, Then, Else>;
 
     case_t(When when, Then then, Else else_) : _when(when), _then(then), _else(else_)
diff --git a/include/sqlpp11/column.h b/include/sqlpp11/column.h
index 8915677f..547c342c 100644
--- a/include/sqlpp11/column.h
+++ b/include/sqlpp11/column.h
@@ -39,13 +39,14 @@
 
 namespace sqlpp
 {
+#warning: need to reactivate column operators?
   template <typename Table, typename ColumnSpec>
-  struct column_t : public expression_operators<column_t<Table, ColumnSpec>, value_type_of<ColumnSpec>>,
-                    public column_operators<column_t<Table, ColumnSpec>, value_type_of<ColumnSpec>>
+  struct column_t// : public expression_operators<column_t<Table, ColumnSpec>, typename ColumnSpec::value_type>,
+                 //   public column_operators<column_t<Table, ColumnSpec>, typename ColumnSpec::value_type>
   {
     struct _traits
     {
-      using _value_type = value_type_of<ColumnSpec>;
+      using _value_type = typename ColumnSpec::value_type;
       using _tags = detail::make_joined_set_t<detail::type_set<tag::is_column, tag::is_expression, tag::is_selectable>,
                                               typename ColumnSpec::_traits::_tags>;
     };
@@ -59,12 +60,7 @@ namespace sqlpp
     using _alias_t = typename _spec_t::_alias_t;
 
     template <typename T>
-    using _is_valid_assignment_operand = is_valid_assignment_operand<value_type_of<ColumnSpec>, T>;
-
-    // disambiguation for C++20 / clang
-    // (see https://bugs.llvm.org/show_bug.cgi?id=46508)
-    using expression_operators<column_t<Table, ColumnSpec>, value_type_of<ColumnSpec>>::operator==;
-    using expression_operators<column_t<Table, ColumnSpec>, value_type_of<ColumnSpec>>::operator!=;
+    using _is_valid_assignment_operand = is_valid_assignment_operand<typename ColumnSpec::value_type, T>;
 
     column_t() = default;
     column_t(const column_t&) = default;
@@ -112,6 +108,12 @@ namespace sqlpp
     }
   };
 
+  template<typename Table, typename ColumnSpec>
+  struct value_type_of<column_t<Table, ColumnSpec>>
+  {
+    using type = typename ColumnSpec::value_type;
+  };
+
   template <typename Context, typename Table, typename ColumnSpec>
   Context& serialize(const column_t<Table, ColumnSpec>&, Context& context)
   {
diff --git a/include/sqlpp11/comparison_expression.h b/include/sqlpp11/comparison_expression.h
new file mode 100644
index 00000000..8990dc8d
--- /dev/null
+++ b/include/sqlpp11/comparison_expression.h
@@ -0,0 +1,83 @@
+#pragma once
+
+/*
+Copyright (c) 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <utility>
+
+#include <sqlpp11/type_traits.h>
+
+namespace sqlpp
+{
+  template <typename L, typename Operator, typename R>
+  struct comparison_expression
+  {
+    L l;
+    R r;
+  };
+
+  template <typename L, typename R>
+  using check_comparison_args = std::enable_if_t<values_are_comparable<L, R>::value>;
+
+#if 0
+  template <typename L, typename Operator, typename R>
+  struct nodes_of<comparison_expression<L, Operator, R>>
+  {
+    using type = type_vector<L, R>;
+  };
+
+  SQLPP_WRAPPED_STATIC_ASSERT(assert_comparison_operands_are_compatible,
+                              "comparison operands must have compatible value types");
+
+  template <typename L, typename R>
+  constexpr auto check_comparison_args()
+  {
+    if constexpr (not values_are_compatible_v<L, R>)
+    {
+      return failed<assert_comparison_operands_are_compatible>{};
+    }
+    else
+    {
+      return succeeded{};
+    }
+  }
+
+  template <typename L, typename Operator, typename R>
+  struct value_type_of_t<comparison_expression<L, Operator, R>>
+  {
+    using type = bool;
+  };
+
+  template <typename L, typename Operator, typename R>
+  constexpr auto requires_braces_v<comparison_expression<L, Operator, R>> = true;
+
+  template <typename Context, typename L, typename Operator, typename R>
+  [[nodiscard]] auto to_sql_string(Context& context, const comparison_expression<L, Operator, R>& t)
+  {
+    return to_sql_string(context, embrace(t.l)) + Operator::symbol + to_sql_string(context, embrace(t.r));
+  }
+#endif
+}  // namespace sqlpp
diff --git a/include/sqlpp11/cte.h b/include/sqlpp11/cte.h
index 0af0f86a..c6e047a7 100644
--- a/include/sqlpp11/cte.h
+++ b/include/sqlpp11/cte.h
@@ -94,9 +94,7 @@ namespace sqlpp
   {
     using _alias_t = typename FieldSpec::_alias_t;
 
-    using _traits = make_traits<value_type_of<FieldSpec>,
-                                tag::must_not_insert,
-                                tag::must_not_update,
+    using _traits = make_traits<value_type_of_t<FieldSpec>,
                                 tag_if<tag::can_be_null, column_spec_can_be_null_t<FieldSpec>::value>>;
   };
 
diff --git a/include/sqlpp11/data_types/boolean/expression_operators.h b/include/sqlpp11/data_types/boolean/expression_operators.h
index 06893154..3a301b50 100644
--- a/include/sqlpp11/data_types/boolean/expression_operators.h
+++ b/include/sqlpp11/data_types/boolean/expression_operators.h
@@ -38,6 +38,7 @@ namespace sqlpp
   {
   };
 
+  /*
   template <typename L, typename R>
   struct return_type_and<L, R, unwrapped_binary_operand_check_t<L, is_boolean_t, R, is_boolean_t>>
   {
@@ -58,4 +59,5 @@ namespace sqlpp
     using check = consistent_t;
     using type = logical_not_t<wrap_operand_t<T>>;
   };
+  */
 }  // namespace sqlpp
diff --git a/include/sqlpp11/data_types/integral/expression_operators.h b/include/sqlpp11/data_types/integral/expression_operators.h
index b0393f94..b0f71e98 100644
--- a/include/sqlpp11/data_types/integral/expression_operators.h
+++ b/include/sqlpp11/data_types/integral/expression_operators.h
@@ -45,7 +45,7 @@ namespace sqlpp
   struct return_type_plus<L, R, binary_operand_check_t<L, is_integral_t, R, is_numeric_not_unsigned_t>>
   {
     using check = consistent_t;
-    using type = plus_t<wrap_operand_t<L>, value_type_of<wrap_operand_t<R>>, wrap_operand_t<R>>;
+    using type = plus_t<wrap_operand_t<L>, value_type_of_t<wrap_operand_t<R>>, wrap_operand_t<R>>;
   };
 
   template <typename L, typename R>
@@ -59,7 +59,7 @@ namespace sqlpp
   struct return_type_minus<L, R, binary_operand_check_t<L, is_integral_t, R, is_numeric_not_unsigned_t>>
   {
     using check = consistent_t;
-    using type = minus_t<wrap_operand_t<L>, value_type_of<wrap_operand_t<R>>, wrap_operand_t<R>>;
+    using type = minus_t<wrap_operand_t<L>, value_type_of_t<wrap_operand_t<R>>, wrap_operand_t<R>>;
   };
 
   template <typename L, typename R>
@@ -73,7 +73,7 @@ namespace sqlpp
   struct return_type_multiplies<L, R, binary_operand_check_t<L, is_integral_t, R, is_numeric_not_unsigned_t>>
   {
     using check = consistent_t;
-    using type = multiplies_t<wrap_operand_t<L>, value_type_of<wrap_operand_t<R>>, wrap_operand_t<R>>;
+    using type = multiplies_t<wrap_operand_t<L>, value_type_of_t<wrap_operand_t<R>>, wrap_operand_t<R>>;
   };
 
   template <typename L, typename R>
diff --git a/include/sqlpp11/data_types/integral/operand.h b/include/sqlpp11/data_types/integral/operand.h
index 9a615b02..232cd868 100644
--- a/include/sqlpp11/data_types/integral/operand.h
+++ b/include/sqlpp11/data_types/integral/operand.h
@@ -58,10 +58,50 @@ namespace sqlpp
     _value_t _t;
   };
 
+  struct optional_integral_operand : public alias_operators<optional_integral_operand>
+  {
+    using _traits = make_traits<integral, tag::is_expression, tag::is_wrapped_value>;
+    using _nodes = detail::type_vector<>;
+    using _is_literal_expression = std::true_type;
+
+    using _value_t = sqlpp::compat::optional<int64_t>;
+    using _can_be_null = std::true_type;
+
+    optional_integral_operand() : _t{}
+    {
+    }
+
+    optional_integral_operand(_value_t t) : _t(t)
+    {
+    }
+
+    optional_integral_operand(const optional_integral_operand&) = default;
+    optional_integral_operand(optional_integral_operand&&) = default;
+    optional_integral_operand& operator=(const optional_integral_operand&) = default;
+    optional_integral_operand& operator=(optional_integral_operand&&) = default;
+    ~optional_integral_operand() = default;
+
+    _value_t _t;
+  };
+
   template <typename Context>
   Context& serialize(const integral_operand& t, Context& context)
   {
     context << t._t;
     return context;
   }
+
+  template <typename Context>
+  Context& serialize(const optional_integral_operand& t, Context& context)
+  {
+    if (t._t.has_value())
+    {
+      context << t._t.value();
+    }
+    else
+    {
+      context << "NULL";
+    }
+    return context;
+  }
 }  // namespace sqlpp
diff --git a/include/sqlpp11/data_types/integral/wrap_operand.h b/include/sqlpp11/data_types/integral/wrap_operand.h
index ffdf46ab..e87e063f 100644
--- a/include/sqlpp11/data_types/integral/wrap_operand.h
+++ b/include/sqlpp11/data_types/integral/wrap_operand.h
@@ -32,6 +32,7 @@
 namespace sqlpp
 {
   struct integral_operand;
+  struct optional_integral_operand;
 
   template <typename T>
   struct wrap_operand<T,
@@ -40,4 +41,12 @@ namespace sqlpp
   {
     using type = integral_operand;
   };
+
+  template <typename T>
+  struct wrap_operand<sqlpp::compat::optional<T>,
+                      typename std::enable_if<std::is_integral<T>::value and not std::is_same<bool, T>::value and
+                                              not std::is_unsigned<T>::value>::type>
+  {
+    using type = optional_integral_operand;
+  };
 }  // namespace sqlpp
diff --git a/include/sqlpp11/data_types/text/expression_operators.h b/include/sqlpp11/data_types/text/expression_operators.h
index 08f40880..88d3bba8 100644
--- a/include/sqlpp11/data_types/text/expression_operators.h
+++ b/include/sqlpp11/data_types/text/expression_operators.h
@@ -52,13 +52,6 @@ namespace sqlpp
   {
     template <typename T>
     using _is_valid_operand = is_valid_operand<text, T>;
-
-    template <typename R>
-    auto like(const R& r) const -> return_type_like_t<Expression, R>
-    {
-      return_type_like<Expression, R>::check::verify();
-      return {*static_cast<const Expression*>(this), wrap_operand_t<R>{r}};
-    }
   };
 
   template <typename L, typename R>
diff --git a/include/sqlpp11/data_types/unsigned_integral/expression_operators.h b/include/sqlpp11/data_types/unsigned_integral/expression_operators.h
index c025b2c5..bf99c570 100644
--- a/include/sqlpp11/data_types/unsigned_integral/expression_operators.h
+++ b/include/sqlpp11/data_types/unsigned_integral/expression_operators.h
@@ -47,14 +47,14 @@ namespace sqlpp
   struct return_type_plus<L, R, binary_operand_check_t<L, is_unsigned_integral_t, R, is_numeric_t>>
   {
     using check = consistent_t;
-    using type = plus_t<wrap_operand_t<L>, value_type_of<wrap_operand_t<R>>, wrap_operand_t<R>>;
+    using type = plus_t<wrap_operand_t<L>, value_type_of_t<wrap_operand_t<R>>, wrap_operand_t<R>>;
   };
 
   template <typename L, typename R>
   struct return_type_minus<L, R, binary_operand_check_t<L, is_unsigned_integral_t, R, is_numeric_not_unsigned_t>>
   {
     using check = consistent_t;
-    using type = minus_t<wrap_operand_t<L>, value_type_of<wrap_operand_t<R>>, wrap_operand_t<R>>;
+    using type = minus_t<wrap_operand_t<L>, value_type_of_t<wrap_operand_t<R>>, wrap_operand_t<R>>;
   };
 
   template <typename L, typename R>
@@ -68,7 +68,7 @@ namespace sqlpp
   struct return_type_multiplies<L, R, binary_operand_check_t<L, is_unsigned_integral_t, R, is_numeric_t>>
   {
     using check = consistent_t;
-    using type = multiplies_t<wrap_operand_t<L>, value_type_of<wrap_operand_t<R>>, wrap_operand_t<R>>;
+    using type = multiplies_t<wrap_operand_t<L>, value_type_of_t<wrap_operand_t<R>>, wrap_operand_t<R>>;
   };
 
   template <typename L, typename R>
diff --git a/include/sqlpp11/eval.h b/include/sqlpp11/eval.h
index 7c548451..29229057 100644
--- a/include/sqlpp11/eval.h
+++ b/include/sqlpp11/eval.h
@@ -42,7 +42,7 @@ namespace sqlpp
     static_assert(required_tables_of<Expr>::size::value == 0,
                   "Expression cannot be used in eval because it requires tables");
     using _name_type = alias::a_t::_alias_t;
-    using _value_type = value_type_of<Expr>;
+    using _value_type = value_type_of_t<Expr>;
     using _field_spec = field_spec_t<_name_type, _value_type, true>;
     using type = typename _field_spec::cpp_type;
   };
diff --git a/include/sqlpp11/exists.h b/include/sqlpp11/exists.h
deleted file mode 100644
index e4925355..00000000
--- a/include/sqlpp11/exists.h
+++ /dev/null
@@ -1,94 +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/char_sequence.h>
-#include <sqlpp11/data_types/boolean.h>
-
-namespace sqlpp
-{
-  struct exists_alias_t
-  {
-    struct _alias_t
-    {
-      static constexpr const char _literal[] = "exists_";
-      using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
-      template <typename T>
-      struct _member_t
-      {
-        T exists;
-        T& operator()()
-        {
-          return exists;
-        }
-        const T& operator()() const
-        {
-          return exists;
-        }
-      };
-    };
-  };
-
-  template <typename Select>
-  struct exists_t : public expression_operators<exists_t<Select>, boolean>, public alias_operators<exists_t<Select>>
-  {
-    using _traits = make_traits<boolean, tag::is_expression, tag::is_selectable>;
-    using _nodes = detail::type_vector<Select>;
-    using _can_be_null = std::false_type;
-
-    static_assert(is_select_t<Select>::value, "exists() requires a select expression as argument");
-
-    using _auto_alias_t = exists_alias_t;
-
-    exists_t(Select select) : _select(select)
-    {
-    }
-
-    exists_t(const exists_t&) = default;
-    exists_t(exists_t&&) = default;
-    exists_t& operator=(const exists_t&) = default;
-    exists_t& operator=(exists_t&&) = default;
-    ~exists_t() = default;
-
-    Select _select;
-  };
-
-  template <typename Context, typename Select>
-  Context& serialize(const exists_t<Select>& t, Context& context)
-  {
-    context << "EXISTS";
-    serialize_operand(t._select, context);
-    return context;
-  }
-
-  template <typename T>
-  auto exists(T t) -> exists_t<wrap_operand_t<T>>
-  {
-    static_assert(is_select_t<wrap_operand_t<T>>::value, "exists() requires a select expression as argument");
-    return {t};
-  }
-}  // namespace sqlpp
diff --git a/include/sqlpp11/expression.h b/include/sqlpp11/expression.h
index 17e71eb6..3db047dd 100644
--- a/include/sqlpp11/expression.h
+++ b/include/sqlpp11/expression.h
@@ -137,10 +137,10 @@ namespace sqlpp
   }
 
   template <typename Lhs, typename O, typename Rhs>
-  struct binary_expression_t : public expression_operators<binary_expression_t<Lhs, O, Rhs>, value_type_of<O>>,
+  struct binary_expression_t : public expression_operators<binary_expression_t<Lhs, O, Rhs>, value_type_of_t<O>>,
                                public alias_operators<binary_expression_t<Lhs, O, Rhs>>
   {
-    using _traits = make_traits<value_type_of<O>, tag::is_expression>;
+    using _traits = make_traits<value_type_of_t<O>, tag::is_expression>;
     using _nodes = detail::type_vector<Lhs, Rhs>;
 
     binary_expression_t(Lhs lhs, Rhs rhs) : _lhs(lhs), _rhs(rhs)
@@ -169,10 +169,10 @@ namespace sqlpp
   }
 
   template <typename O, typename Rhs>
-  struct unary_expression_t : public expression_operators<unary_expression_t<O, Rhs>, value_type_of<O>>,
+  struct unary_expression_t : public expression_operators<unary_expression_t<O, Rhs>, value_type_of_t<O>>,
                               public alias_operators<unary_expression_t<O, Rhs>>
   {
-    using _traits = make_traits<value_type_of<O>, tag::is_expression>;
+    using _traits = make_traits<value_type_of_t<O>, tag::is_expression>;
     using _nodes = detail::type_vector<Rhs>;
 
     unary_expression_t(Rhs rhs) : _rhs(rhs)
diff --git a/include/sqlpp11/expression_return_types.h b/include/sqlpp11/expression_return_types.h
index b1048f0c..c095cd52 100644
--- a/include/sqlpp11/expression_return_types.h
+++ b/include/sqlpp11/expression_return_types.h
@@ -97,7 +97,7 @@ namespace sqlpp
   struct return_type_plus
   {
     using check = assert_valid_operands;
-    using type = bad_expression<value_type_of<L>>;
+    using type = bad_expression<value_type_of_t<L>>;
   };
   template <typename L, typename R>
   using return_type_plus_t = typename return_type_plus<L, R>::type;
@@ -106,7 +106,7 @@ namespace sqlpp
   struct return_type_minus
   {
     using check = assert_valid_operands;
-    using type = bad_expression<value_type_of<L>>;
+    using type = bad_expression<value_type_of_t<L>>;
   };
   template <typename L, typename R>
   using return_type_minus_t = typename return_type_minus<L, R>::type;
@@ -115,7 +115,7 @@ namespace sqlpp
   struct return_type_multiplies
   {
     using check = assert_valid_operands;
-    using type = bad_expression<value_type_of<L>>;
+    using type = bad_expression<value_type_of_t<L>>;
   };
   template <typename L, typename R>
   using return_type_multiplies_t = typename return_type_multiplies<L, R>::type;
@@ -124,7 +124,7 @@ namespace sqlpp
   struct return_type_divides
   {
     using check = assert_valid_operands;
-    using type = bad_expression<value_type_of<L>>;
+    using type = bad_expression<value_type_of_t<L>>;
   };
   template <typename L, typename R>
   using return_type_divides_t = typename return_type_divides<L, R>::type;
@@ -133,7 +133,7 @@ namespace sqlpp
   struct return_type_modulus
   {
     using check = assert_valid_operands;
-    using type = bad_expression<value_type_of<L>>;
+    using type = bad_expression<value_type_of_t<L>>;
   };
   template <typename L, typename R>
   using return_type_modulus_t = typename return_type_modulus<L, R>::type;
@@ -142,7 +142,7 @@ namespace sqlpp
   struct return_type_unary_plus
   {
     using check = assert_valid_operands;
-    using type = bad_expression<value_type_of<T>>;
+    using type = bad_expression<value_type_of_t<T>>;
   };
   template <typename T, typename Defer>
   using return_type_unary_plus_t = typename return_type_unary_plus<T, Defer>::type;
@@ -151,7 +151,7 @@ namespace sqlpp
   struct return_type_unary_minus
   {
     using check = assert_valid_operands;
-    using type = bad_expression<value_type_of<T>>;
+    using type = bad_expression<value_type_of_t<T>>;
   };
   template <typename T, typename Defer>
   using return_type_unary_minus_t = typename return_type_unary_minus<T, Defer>::type;
diff --git a/include/sqlpp11/field_spec.h b/include/sqlpp11/field_spec.h
index 7ba5ae83..96a19c6b 100644
--- a/include/sqlpp11/field_spec.h
+++ b/include/sqlpp11/field_spec.h
@@ -37,11 +37,6 @@ namespace sqlpp
   template <typename NameType, typename ValueType, bool CanBeNull>
   struct field_spec_t
   {
-    using _traits = make_traits<ValueType,
-                                tag::is_noop,
-                                tag_if<tag::can_be_null, CanBeNull>>;
-    using _nodes = detail::type_vector<>;
-
     using _alias_t = NameType;
 
     using cpp_type = typename std::conditional<CanBeNull,
@@ -77,13 +72,14 @@ namespace sqlpp
     struct make_field_spec_impl
     {
       using RawNamedExpr = remove_optional_t<NamedExpr>;
-      static constexpr bool _can_be_null = is_optional<NamedExpr>::value or can_be_null_t<RawNamedExpr>::value;
+      using ValueType = value_type_of_t<RawNamedExpr>;
+      static constexpr bool _can_be_null = is_optional<ValueType>::value or is_optional<NamedExpr>::value;
       static constexpr bool _depends_on_outer_table =
           detail::make_intersect_set_t<required_tables_of<RawNamedExpr>,
                                        typename Select::_used_outer_tables>::size::value > 0;
 
       using type = field_spec_t<typename RawNamedExpr::_alias_t,
-                                value_type_of<RawNamedExpr>,
+                                remove_optional_t<ValueType>,
                                 logic::any_t<_can_be_null, _depends_on_outer_table>::value>;
     };
   }  // namespace detail
diff --git a/include/sqlpp11/functions.h b/include/sqlpp11/functions.h
index acf0e680..b2f0d41e 100644
--- a/include/sqlpp11/functions.h
+++ b/include/sqlpp11/functions.h
@@ -39,7 +39,6 @@
 #include <sqlpp11/not_in.h>
 #include <sqlpp11/is_null.h>
 #include <sqlpp11/is_not_null.h>
-#include <sqlpp11/exists.h>
 #include <sqlpp11/any.h>
 #include <sqlpp11/some.h>
 #include <sqlpp11/value_type.h>
@@ -54,7 +53,7 @@
 namespace sqlpp
 {
   template <typename Expression, typename Db>
-  auto flatten(const Expression& exp, Db& db) -> verbatim_t<value_type_of<Expression>>
+  auto flatten(const Expression& exp, Db& db) -> verbatim_t<value_type_of_t<Expression>>
   {
     static_assert(not make_parameter_list_t<Expression>::size::value,
                   "parameters are not allowed in flattened expressions");
diff --git a/include/sqlpp11/insert_value.h b/include/sqlpp11/insert_value.h
index e7ed389c..259e0958 100644
--- a/include/sqlpp11/insert_value.h
+++ b/include/sqlpp11/insert_value.h
@@ -58,7 +58,7 @@ namespace sqlpp
   {
     using _is_insert_value = std::true_type;
     using _column_t = Column;
-    using _pure_value_t = typename value_type_of<Column>::_cpp_value_type;
+    using _pure_value_t = typename value_type_of_t<Column>::_cpp_value_type;
     using _wrapped_value_t = wrap_operand_t<_pure_value_t>;
     using _value_or_null_t = value_or_null_t<typename Column::_traits::_value_type>;
 
diff --git a/include/sqlpp11/insert_value_list.h b/include/sqlpp11/insert_value_list.h
index 0e2e7e04..9f103865 100644
--- a/include/sqlpp11/insert_value_list.h
+++ b/include/sqlpp11/insert_value_list.h
@@ -138,8 +138,6 @@ namespace sqlpp
 
   SQLPP_PORTABLE_STATIC_ASSERT(assert_insert_set_assignments_t, "at least one argument is not an assignment in set()");
   SQLPP_PORTABLE_STATIC_ASSERT(assert_insert_set_no_duplicates_t, "at least one duplicate column detected in set()");
-  SQLPP_PORTABLE_STATIC_ASSERT(assert_insert_set_allowed_t,
-                               "at least one assignment is prohibited by its column definition in set()");
   SQLPP_PORTABLE_STATIC_ASSERT(assert_insert_set_single_table_t,
                                "set() arguments contain assignments from more than one table");
   SQLPP_PORTABLE_STATIC_ASSERT(assert_insert_static_set_count_args_t,
@@ -149,31 +147,12 @@ namespace sqlpp
   SQLPP_PORTABLE_STATIC_ASSERT(assert_insert_dynamic_set_statement_dynamic_t,
                                "dynamic_set must not be called in a static statement");
 
-  // workaround for msvc bugs https://connect.microsoft.com/VisualStudio/Feedback/Details/2173269 &
-  // https://connect.microsoft.com/VisualStudio/Feedback/Details/2173198
-  //  template <typename... Assignments>
-  //  using check_insert_set_t = static_combined_check_t<
-  //      static_check_t<logic::all_t<is_assignment_t<Assignments>::value...>::value, assert_insert_set_assignments_t>,
-  //      static_check_t<not detail::has_duplicates<lhs_t<Assignments>...>::value, assert_insert_set_no_duplicates_t>,
-  //      static_check_t<logic::none_t<must_not_insert_t<lhs_t<Assignments>>::value...>::value,
-  //                     assert_insert_set_allowed_t>,
-  //      static_check_t<sizeof...(Assignments) == 0 or
-  //                         detail::make_joined_set_t<required_tables_of<lhs_t<Assignments>>...>::size::value == 1,
-  //                     assert_insert_set_single_table_t>>;
-
-  template <typename Expr>
-  struct must_not_insert
-  {
-    static const bool value = must_not_insert_t<lhs_t<Expr>>::value;
-  };
-
   template <typename... Assignments>
   using check_insert_set_t = static_combined_check_t<
       static_check_t<logic::all_t<detail::is_assignment_impl<Assignments>::type::value...>::value,
                      assert_insert_set_assignments_t>,
       static_check_t<not detail::has_duplicates<typename lhs<Assignments>::type...>::value,
                      assert_insert_set_no_duplicates_t>,
-      static_check_t<logic::none_t<must_not_insert<Assignments>::value...>::value, assert_insert_set_allowed_t>,
       static_check_t<sizeof...(Assignments) == 0 or detail::make_joined_set_t<required_tables_of<
                                                         typename lhs<Assignments>::type>...>::size::value == 1,
                      assert_insert_set_single_table_t>>;
@@ -382,8 +361,6 @@ namespace sqlpp
       {
         static_assert(not detail::has_duplicates<Columns...>::value,
                       "at least one duplicate argument detected in columns()");
-        static_assert(logic::none_t<must_not_insert_t<Columns>::value...>::value,
-                      "at least one column argument has a must_not_insert tag in its definition");
         using _column_required_tables = detail::make_joined_set_t<required_tables_of<Columns>...>;
         static_assert(_column_required_tables::size::value == 1, "columns() contains columns from several tables");
 
diff --git a/include/sqlpp11/is_equal_to_or_null.h b/include/sqlpp11/is_equal_to_or_null.h
index 3e17f2e1..72096b37 100644
--- a/include/sqlpp11/is_equal_to_or_null.h
+++ b/include/sqlpp11/is_equal_to_or_null.h
@@ -68,7 +68,7 @@ namespace sqlpp
   {
     static_assert(is_expression_t<Expr>::value,
                   "is_equal_to_or_null() is to be called an expression (e.g. a column) and a value_or_null expression");
-    static_assert(std::is_same<value_type_of<Expr>, ValueType>::value,
+    static_assert(std::is_same<value_type_of_t<Expr>, ValueType>::value,
                   "is_equal_to_or_null() arguments need to have the same value type");
     return {expr, value};
   }
diff --git a/include/sqlpp11/logical_expression.h b/include/sqlpp11/logical_expression.h
new file mode 100644
index 00000000..2497bc29
--- /dev/null
+++ b/include/sqlpp11/logical_expression.h
@@ -0,0 +1,123 @@
+#pragma once
+
+/*
+Copyright (c) 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <type_traits>
+
+#include <sqlpp11/alias.h>
+//#include <sqlpp11/bad_expression.h>
+//#include <sqlpp11/embrace.h>
+//#include <sqlpp11/to_sql_string.h>
+#include <sqlpp11/type_traits.h>
+//#include <sqlpp11/wrapped_static_assert.h>
+
+namespace sqlpp
+{
+  template <typename L, typename Operator, typename R>
+  struct logical_expression
+  {
+    logical_expression() = delete;
+    constexpr logical_expression(L l, R r) : _l(l), _r(r)
+    {
+    }
+    logical_expression(const logical_expression&) = default;
+    logical_expression(logical_expression&&) = default;
+    logical_expression& operator=(const logical_expression&) = default;
+    logical_expression& operator=(logical_expression&&) = default;
+    ~logical_expression() = default;
+
+    template <typename alias_provider>
+    expression_alias_t<logical_expression, alias_provider> as(const alias_provider& /*unused*/) const
+    {
+      return {*this};
+    }
+
+    L _l;
+    R _r;
+  };
+
+  template <typename Operator, typename R>
+  struct unary_logical_expression
+  {
+    unary_logical_expression() = delete;
+    constexpr unary_logical_expression(R r) : _r(r)
+    {
+    }
+    unary_logical_expression(const unary_logical_expression&) = default;
+    unary_logical_expression(unary_logical_expression&&) = default;
+    unary_logical_expression& operator=(const unary_logical_expression&) = default;
+    unary_logical_expression& operator=(unary_logical_expression&&) = default;
+    ~unary_logical_expression() = default;
+
+    template <typename alias_provider>
+    expression_alias_t<unary_logical_expression, alias_provider> as(const alias_provider& /*unused*/) const
+    {
+      return {*this};
+    }
+
+    R _r;
+  };
+
+  template <typename L, typename R>
+  using check_logical_args = std::enable_if_t<has_boolean_value<L>::value and has_boolean_value<R>::value>;
+
+  /*
+  template <typename L, typename Operator, typename R>
+  struct nodes_of<logical_binary_expression<L, Operator, R>>
+  {
+    using type = type_vector<L, R>;
+  };
+
+  template <typename L, typename Operator, typename R>
+  struct value_type_of_t<logical_binary_expression<L, Operator, R>>
+  {
+    using type = bool;
+  };
+
+  template <typename L, typename Operator, typename R>
+  constexpr auto requires_braces_v<logical_binary_expression<L, Operator, R>> = true;
+
+  template <typename Context, typename L, typename Operator, typename R>
+  [[nodiscard]] auto to_sql_string(Context& context, const logical_binary_expression<L, Operator, R>& t)
+  {
+    return to_sql_string(context, embrace(t._l)) + Operator::symbol + to_sql_string(context, embrace(t._r));
+  }
+
+  template <typename Context, typename Operator, typename R>
+  [[nodiscard]] auto to_sql_string(Context& context, const logical_binary_expression<none_t, Operator, R>& t)
+  {
+    return Operator::symbol + to_sql_string(context, embrace(t._r));
+  }
+
+  template <typename Context, typename L1, typename Operator, typename R1, typename R2>
+  [[nodiscard]] auto to_sql_string(Context& context, const logical_binary_expression<logical_binary_expression<L1, Operator, R1>, Operator, R2>& t)
+  {
+    return to_sql_string(context, t._l) + Operator::symbol + to_sql_string(context, embrace(t._r));
+  }
+  */
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator.h b/include/sqlpp11/operator.h
new file mode 100644
index 00000000..8c9091a0
--- /dev/null
+++ b/include/sqlpp11/operator.h
@@ -0,0 +1,83 @@
+#pragma once
+
+/*
+Copyright (c) 2017 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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.
+*/
+
+/* Hint
+   Most operators are using enable_if instead of wrapped static_assert.
+   This is because variants with static_assert would enter the overload
+   set and cause havoc.
+   */
+
+// logical
+#include <sqlpp11/operator/logical_and.h>
+#include <sqlpp11/operator/logical_not.h>
+#include <sqlpp11/operator/logical_or.h>
+
+// comparison
+#include <sqlpp11/operator/equal_to.h>
+#include <sqlpp11/operator/greater.h>
+#include <sqlpp11/operator/greater_equal.h>
+#include <sqlpp11/operator/less.h>
+#include <sqlpp11/operator/less_equal.h>
+#include <sqlpp11/operator/like.h>
+#include <sqlpp11/operator/not_equal_to.h>
+#include <sqlpp11/operator/is_distinct_from.h>
+#include <sqlpp11/operator/is_not_distinct_from.h>
+#include <sqlpp11/operator/is_not_null.h>
+#include <sqlpp11/operator/is_null.h>
+
+
+// arithmetic
+#include <sqlpp11/operator/divides.h>
+#include <sqlpp11/operator/minus.h>
+#include <sqlpp11/operator/modulus.h>
+#include <sqlpp11/operator/multiplies.h>
+#include <sqlpp11/operator/negate.h>
+#include <sqlpp11/operator/plus.h>
+
+// binary
+#include <sqlpp11/operator/bit_and.h>
+#include <sqlpp11/operator/bit_not.h>
+#include <sqlpp11/operator/bit_or.h>
+#include <sqlpp11/operator/bit_shift_left.h>
+#include <sqlpp11/operator/bit_shift_right.h>
+#include <sqlpp11/operator/bit_xor.h>
+
+// assignment
+#include <sqlpp11/operator/assign.h>
+
+// misc
+#include <sqlpp11/operator/as.h>
+
+#include <sqlpp11/operator/asc.h>
+#include <sqlpp11/operator/desc.h>
+#include <sqlpp11/operator/order.h>
+
+#include <sqlpp11/operator/in.h>
+#include <sqlpp11/operator/not_in.h>
+
+#include <sqlpp11/operator/exists.h>
diff --git a/include/sqlpp11/operator/as.h b/include/sqlpp11/operator/as.h
new file mode 100644
index 00000000..2089f214
--- /dev/null
+++ b/include/sqlpp11/operator/as.h
@@ -0,0 +1,47 @@
+#pragma once
+
+/*
+Copyright (c) 2017, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <type_traits>
+
+#include <sqlpp11/alias.h>
+#include <sqlpp11/type_traits.h>
+
+namespace sqlpp
+{
+  template <typename Expr, typename AliasProvider>
+  using check_as_args = std::enable_if_t<
+  is_expression_t<Expr>::value and not is_alias_t<Expr>::value and has_name<AliasProvider>::value
+  >;
+
+  template <typename Expr, typename AliasProvider, typename = check_as_args<Expr, AliasProvider>>
+  constexpr auto as(Expr expr, const AliasProvider&) -> expression_alias_t<Expr, AliasProvider>
+  {
+      return {std::move(expr)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/asc.h b/include/sqlpp11/operator/asc.h
new file mode 100644
index 00000000..71ae28d7
--- /dev/null
+++ b/include/sqlpp11/operator/asc.h
@@ -0,0 +1,39 @@
+#pragma once
+
+/*
+Copyright (c) 2017 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/sort_order_expression.h>
+
+namespace sqlpp
+{
+  template <typename L, typename = check_sort_order_args<L>>
+  constexpr auto asc(L l) -> sort_order_expression<L>
+  {
+    return {l, sort_order::asc};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/assign.h b/include/sqlpp11/operator/assign.h
new file mode 100644
index 00000000..444ff5ae
--- /dev/null
+++ b/include/sqlpp11/operator/assign.h
@@ -0,0 +1,82 @@
+#pragma once
+
+/*
+Copyright (c) 2017 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <utility>
+
+#include <sqlpp11/type_traits.h>
+#include <sqlpp11/default_value.h>
+
+namespace sqlpp
+{
+  template <typename L, typename R>
+  struct assign_expression
+  {
+    L column;
+    R value;
+  };
+
+#warning rename is_column, is_default, values_are_comparable -> values_are_compatible
+#warning document the change that there is no read-only!
+#warning handle default_t, but only if the column does have a default!
+  template <typename L, typename R>
+  using check_assign_args = std::enable_if_t<is_column_t<L>::value and values_are_comparable<L, R>::value and
+                                             (can_be_null_t<L>::value or not is_optional<R>::value) and
+                                             (has_default_t<L>::value or not std::is_same<R, default_value_t>::value)>;
+
+  template <typename L, typename R, typename = check_assign_args<L, R>>
+  constexpr auto assign(L column, R value) -> assign_expression<L, R>
+  {
+    return {std::move(column), std::move(value)};
+  }
+
+  /*
+  template <typename L, typename R>
+  struct nodes_of<assign_t<L, R>>
+  {
+    using type = type_vector<L, R>;
+  };
+
+  template <typename L, typename R>
+  constexpr auto is_assignment_v<assign_t<L, R>> = true;
+
+  template <typename L, typename R>
+  struct column_of<assign_t<L, R>>
+  {
+    using type = L;
+  };
+
+  template <typename L, typename R>
+  constexpr auto requires_braces_v<assign_t<L, R>> = true;
+
+  template <typename Context, typename L, typename R>
+  [[nodiscard]] auto to_sql_string(Context& context, const assign_t<L, R>& t)
+  {
+    return to_sql_string(context, t.column) + " = " + to_sql_string(context, embrace(t.value));
+  }
+  */
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/bit_and.h b/include/sqlpp11/operator/bit_and.h
new file mode 100644
index 00000000..6b74b25e
--- /dev/null
+++ b/include/sqlpp11/operator/bit_and.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2016 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/bit_expression.h>
+
+namespace sqlpp
+{
+  struct bit_and
+  {
+    static constexpr auto symbol = " & ";
+  };
+
+  template <typename L, typename R, typename = check_bit_expression_args<L, R>>
+  constexpr auto operator&(L l, R r) -> bit_expression<L, bit_and, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/bit_not.h b/include/sqlpp11/operator/bit_not.h
new file mode 100644
index 00000000..bcfe9be6
--- /dev/null
+++ b/include/sqlpp11/operator/bit_not.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2016 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/bit_expression.h>
+
+namespace sqlpp
+{
+  struct bit_not
+  {
+    static constexpr auto symbol = "~";
+  };
+
+  template <typename R, typename = check_bit_expression_args<R, R>>
+  constexpr auto operator~(R r) -> unary_bit_expression<bit_not, R>
+  {
+    return {std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/bit_or.h b/include/sqlpp11/operator/bit_or.h
new file mode 100644
index 00000000..2112d739
--- /dev/null
+++ b/include/sqlpp11/operator/bit_or.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2016 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/bit_expression.h>
+
+namespace sqlpp
+{
+  struct bit_or
+  {
+    static constexpr auto symbol = " | ";
+  };
+
+  template <typename L, typename R, typename = check_bit_expression_args<L, R>>
+  constexpr auto operator|(L l, R r) -> bit_expression<L, bit_or, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/bit_shift_left.h b/include/sqlpp11/operator/bit_shift_left.h
new file mode 100644
index 00000000..5cff1ad9
--- /dev/null
+++ b/include/sqlpp11/operator/bit_shift_left.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2016 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/bit_expression.h>
+
+namespace sqlpp
+{
+  struct bit_shift_left
+  {
+    static constexpr auto symbol = " << ";
+  };
+
+  template <typename L, typename R, typename = check_bit_expression_args<L, R>>
+  constexpr auto operator<<(L l, R r) -> bit_expression<L, bit_shift_left, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/bit_shift_right.h b/include/sqlpp11/operator/bit_shift_right.h
new file mode 100644
index 00000000..5bc19bbb
--- /dev/null
+++ b/include/sqlpp11/operator/bit_shift_right.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2016 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/bit_expression.h>
+
+namespace sqlpp
+{
+  struct bit_shift_right
+  {
+    static constexpr auto symbol = " >> ";
+  };
+
+  template <typename L, typename R, typename = check_bit_expression_args<L, R>>
+  constexpr auto operator>>(L l, R r) -> bit_expression<L, bit_shift_right, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/bit_xor.h b/include/sqlpp11/operator/bit_xor.h
new file mode 100644
index 00000000..cfcf0c51
--- /dev/null
+++ b/include/sqlpp11/operator/bit_xor.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2016 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/bit_expression.h>
+
+namespace sqlpp
+{
+  struct bit_xor
+  {
+    static constexpr auto symbol = " ^ ";
+  };
+
+  template <typename L, typename R, typename = check_bit_expression_args<L, R>>
+  constexpr auto operator^(L l, R r) -> bit_expression<L, bit_xor, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/desc.h b/include/sqlpp11/operator/desc.h
new file mode 100644
index 00000000..b92f4ea2
--- /dev/null
+++ b/include/sqlpp11/operator/desc.h
@@ -0,0 +1,39 @@
+#pragma once
+
+/*
+Copyright (c) 2017 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/sort_order_expression.h>
+
+namespace sqlpp
+{
+  template <typename L, typename = check_sort_order_args<L>>
+  constexpr auto desc(L l) -> sort_order_expression<L>
+  {
+    return {l, sort_order::desc};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/divides.h b/include/sqlpp11/operator/divides.h
new file mode 100644
index 00000000..a19fe50c
--- /dev/null
+++ b/include/sqlpp11/operator/divides.h
@@ -0,0 +1,45 @@
+#pragma once
+
+/*
+Copyright (c) 2016 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <utility>
+
+#include <sqlpp11/arithmetic_expression.h>
+
+namespace sqlpp
+{
+  struct divides
+  {
+    static constexpr auto symbol = " / ";
+  };
+
+  template <typename L, typename R, typename = check_arithmetic_args<L, R>>
+  constexpr auto operator/(L l, R r) -> arithmetic_expression<L, divides, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/equal_to.h b/include/sqlpp11/operator/equal_to.h
new file mode 100644
index 00000000..02e29a90
--- /dev/null
+++ b/include/sqlpp11/operator/equal_to.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2017- 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/comparison_expression.h>
+
+namespace sqlpp
+{
+  struct equal_to
+  {
+    static constexpr auto symbol = " = ";
+  };
+
+  template <typename L, typename R, typename = check_comparison_args<L, R>>
+  constexpr auto operator==(L l, R r) -> comparison_expression<L, equal_to, R>
+  {
+    return {l, r};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/exists.h b/include/sqlpp11/operator/exists.h
new file mode 100644
index 00000000..dd055bff
--- /dev/null
+++ b/include/sqlpp11/operator/exists.h
@@ -0,0 +1,68 @@
+#pragma once
+
+/*
+Copyright (c) 2017 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 SubSelect>
+  struct exists_t
+  {
+    SubSelect sub_select;
+  };
+
+  template <typename SubSelect>
+  using check_exists_arg = std::enable_if_t<is_statement_t<SubSelect>::value and has_result_row_t<SubSelect>::value>;
+
+#warning: Document that functions dont come with their default alias any more
+  template <typename SubSelect, typename = check_exists_arg<SubSelect>>
+  constexpr auto exists(SubSelect sub_select) -> exists_t<SubSelect>
+  {
+    return exists_t<SubSelect>{sub_select};
+  }
+
+  /*
+  template <typename SubSelect>
+  struct nodes_of<exists_t<SubSelect>>
+  {
+    using type = type_vector<SubSelect>;
+  };
+
+  template <typename SubSelect>
+  struct value_type_of_t<exists_t<SubSelect>>
+  {
+    using type = bool;
+  };
+
+  template <typename Context, typename SubSelect>
+  [[nodiscard]] auto to_sql_string(Context& context, const exists_t<SubSelect>& t)
+  {
+    return " EXISTS(" + to_sql_string(context, t.sub_select) + ") ";
+  }
+  */
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/greater.h b/include/sqlpp11/operator/greater.h
new file mode 100644
index 00000000..e5f8281e
--- /dev/null
+++ b/include/sqlpp11/operator/greater.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2017- 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/comparison_expression.h>
+
+namespace sqlpp
+{
+  struct greater
+  {
+    static constexpr auto symbol = " > ";
+  };
+
+  template <typename L, typename R, typename = check_comparison_args<L, R>>
+  constexpr auto operator>(L l, R r) -> comparison_expression<L, greater, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/greater_equal.h b/include/sqlpp11/operator/greater_equal.h
new file mode 100644
index 00000000..ee0c5a97
--- /dev/null
+++ b/include/sqlpp11/operator/greater_equal.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2017- 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/comparison_expression.h>
+
+namespace sqlpp
+{
+  struct greater_equal
+  {
+    static constexpr auto symbol = " >= ";
+  };
+
+  template <typename L, typename R, typename = check_comparison_args<L, R>>
+  constexpr auto operator>=(L l, R r) -> comparison_expression<L, greater_equal, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/in.h b/include/sqlpp11/operator/in.h
new file mode 100644
index 00000000..c5cb8de9
--- /dev/null
+++ b/include/sqlpp11/operator/in.h
@@ -0,0 +1,60 @@
+#pragma once
+
+/*
+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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <tuple>
+#include <vector>
+
+#include <sqlpp11/in_expression.h>
+
+namespace sqlpp
+{
+  struct operator_in
+  {
+    static constexpr auto symbol = " IN ";
+  };
+
+#warning: something.in(select(...)); should be suppported as is
+  template <typename L, typename... Args, typename = check_in_args<L, Args...>>
+  constexpr auto in(L l, std::tuple<Args...> args) -> in_expression<L, operator_in, std::tuple<Args...>>
+  {
+    return {std::move(l), std::move(args)};
+  }
+
+  template <typename L, typename... Args, typename = check_in_args<L, Args...>>
+  constexpr auto in(L l, Args... args) -> in_expression<L, operator_in, std::tuple<Args...>>
+  {
+    return {std::move(l), std::make_tuple(std::move(args)...)};
+  }
+
+  template <typename L, typename Arg, typename = check_in_args<L, Arg>>
+  constexpr auto in(L l, std::vector<Arg> args) -> in_expression<L, operator_in, std::vector<Arg>>
+  {
+    return {std::move(l), std::move(args)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/is_distinct_from.h b/include/sqlpp11/operator/is_distinct_from.h
new file mode 100644
index 00000000..f53d439a
--- /dev/null
+++ b/include/sqlpp11/operator/is_distinct_from.h
@@ -0,0 +1,46 @@
+#pragma once
+
+/*
+Copyright (c) 2017- 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/comparison_expression.h>
+
+namespace sqlpp
+{
+  struct is_distinct_from
+  {
+    static constexpr auto symbol = " IS DISTINCT FROM "; // sql standard
+    // mysql has NULL-safe equal `<=>` which is equivalent to `IS NOT DISTINCT FROM`
+    // sqlite3 has `IS NOT`
+  };
+
+  template <typename L, typename R, typename = check_comparison_args<L, R>>
+  constexpr auto is_distinct_from(L l, R r) -> comparison_expression<L, is_distinct_from, R>
+  {
+    return {l, r};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/is_not_distinct_from.h b/include/sqlpp11/operator/is_not_distinct_from.h
new file mode 100644
index 00000000..0347a0c2
--- /dev/null
+++ b/include/sqlpp11/operator/is_not_distinct_from.h
@@ -0,0 +1,46 @@
+#pragma once
+
+/*
+Copyright (c) 2017- 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/comparison_expression.h>
+
+namespace sqlpp
+{
+  struct is_not_distinct_from
+  {
+    static constexpr auto symbol = " IS NOT DISTINCT FROM "; // sql standard
+    // mysql has NULL-safe equal `<=>`
+    // sqlite3 has `IS`
+  };
+
+  template <typename L, typename R, typename = check_comparison_args<L, R>>
+  constexpr auto is_not_distinct_from(L l, R r) -> comparison_expression<L, is_not_distinct_from, R>
+  {
+    return {l, r};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/is_not_null.h b/include/sqlpp11/operator/is_not_null.h
new file mode 100644
index 00000000..85f2f02a
--- /dev/null
+++ b/include/sqlpp11/operator/is_not_null.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2017 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/comparison_expression.h>
+
+namespace sqlpp
+{
+  struct is_not
+  {
+    static constexpr auto symbol = " IS NOT ";
+  };
+
+  template <typename L>
+  constexpr auto is_null(L l) -> comparison_expression<L, is_not, sqlpp::compat::nullopt_t>
+  {
+    return {l};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/is_null.h b/include/sqlpp11/operator/is_null.h
new file mode 100644
index 00000000..60f88769
--- /dev/null
+++ b/include/sqlpp11/operator/is_null.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2017 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/comparison_expression.h>
+
+namespace sqlpp
+{
+  struct is
+  {
+    static constexpr auto symbol = " IS ";
+  };
+
+  template <typename L>
+  constexpr auto is_null(L l) -> comparison_expression<L, is, sqlpp::compat::nullopt_t>
+  {
+    return {l};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/less.h b/include/sqlpp11/operator/less.h
new file mode 100644
index 00000000..6b2fb94e
--- /dev/null
+++ b/include/sqlpp11/operator/less.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2017- 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/comparison_expression.h>
+
+namespace sqlpp
+{
+  struct less
+  {
+    static constexpr auto symbol = " < ";
+  };
+
+  template <typename L, typename R, typename = check_comparison_args<L, R>>
+  constexpr auto operator<(L l, R r) -> comparison_expression<L, less, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/less_equal.h b/include/sqlpp11/operator/less_equal.h
new file mode 100644
index 00000000..b2a22548
--- /dev/null
+++ b/include/sqlpp11/operator/less_equal.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2017- 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/comparison_expression.h>
+
+namespace sqlpp
+{
+  struct less_equal
+  {
+    static constexpr auto symbol = " <= ";
+  };
+
+  template <typename L, typename R, typename = check_comparison_args<L, R>>
+  constexpr auto operator<=(L l, R r) -> comparison_expression<L, less_equal, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/like.h b/include/sqlpp11/operator/like.h
new file mode 100644
index 00000000..cd465bbb
--- /dev/null
+++ b/include/sqlpp11/operator/like.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2017- 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/comparison_expression.h>
+
+namespace sqlpp
+{
+  struct operator_like
+  {
+    static constexpr auto symbol = " LIKE ";
+  };
+
+  template <typename L, typename R, typename = check_comparison_args<L, R>>
+  constexpr auto like(L l, R r) -> comparison_expression<L, operator_like, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/logical_and.h b/include/sqlpp11/operator/logical_and.h
new file mode 100644
index 00000000..15c22c87
--- /dev/null
+++ b/include/sqlpp11/operator/logical_and.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2017, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/logical_expression.h>
+
+namespace sqlpp
+{
+  struct logical_and
+  {
+    static constexpr auto symbol = " AND ";
+  };
+
+  template <typename L, typename R, typename = check_logical_args<L, R>>
+  constexpr auto operator and(L l, R r) -> logical_expression<L, logical_and, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/logical_not.h b/include/sqlpp11/operator/logical_not.h
new file mode 100644
index 00000000..ab7b4539
--- /dev/null
+++ b/include/sqlpp11/operator/logical_not.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2017, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/logical_expression.h>
+
+namespace sqlpp
+{
+  struct logical_not
+  {
+    static constexpr auto symbol = "NOT ";
+  };
+
+  template <typename R, typename = check_logical_args<R, R>>
+  constexpr auto operator!(R r) -> unary_logical_expression<logical_not, R>
+  {
+    return {std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/logical_or.h b/include/sqlpp11/operator/logical_or.h
new file mode 100644
index 00000000..401e637c
--- /dev/null
+++ b/include/sqlpp11/operator/logical_or.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2017, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/logical_expression.h>
+
+namespace sqlpp
+{
+  struct logical_or
+  {
+    static constexpr auto symbol = " OR ";
+  };
+
+  template <typename L, typename R, typename = check_logical_args<L, R>>
+  constexpr auto operator||(L l, R r) -> logical_expression<L, logical_or, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/minus.h b/include/sqlpp11/operator/minus.h
new file mode 100644
index 00000000..e3538b38
--- /dev/null
+++ b/include/sqlpp11/operator/minus.h
@@ -0,0 +1,45 @@
+#pragma once
+
+/*
+Copyright (c) 2016 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <utility>
+
+#include <sqlpp11/arithmetic_expression.h>
+
+namespace sqlpp
+{
+  struct minus
+  {
+    static constexpr auto symbol = " - ";
+  };
+
+  template <typename L, typename R, typename = check_arithmetic_args<L, R>>
+  constexpr auto operator-(L l, R r) -> arithmetic_expression<L, minus, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/modulus.h b/include/sqlpp11/operator/modulus.h
new file mode 100644
index 00000000..872ff242
--- /dev/null
+++ b/include/sqlpp11/operator/modulus.h
@@ -0,0 +1,49 @@
+#pragma once
+
+/*
+Copyright (c) 2016 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <utility>
+
+#include <sqlpp11/arithmetic_expression.h>
+#include <sqlpp11/type_traits.h>
+
+namespace sqlpp
+{
+  struct modulus
+  {
+    static constexpr auto symbol = " % ";
+  };
+
+  template <typename L, typename R>
+  using check_modulus_args = std::enable_if_t<has_integral_value<L>::value and has_integral_value<R>::value>;
+
+  template <typename L, typename R, typename = check_modulus_args<L, R>>
+  constexpr auto operator%(L l, R r) -> arithmetic_expression<L, modulus, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/multiplies.h b/include/sqlpp11/operator/multiplies.h
new file mode 100644
index 00000000..c021280b
--- /dev/null
+++ b/include/sqlpp11/operator/multiplies.h
@@ -0,0 +1,45 @@
+#pragma once
+
+/*
+Copyright (c) 2016 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <utility>
+
+#include <sqlpp11/arithmetic_expression.h>
+
+namespace sqlpp
+{
+  struct multiplies
+  {
+    static constexpr auto symbol = " * ";
+  };
+
+  template <typename L, typename R, typename = check_arithmetic_args<L, R>>
+  constexpr auto operator*(L l, R r) -> arithmetic_expression<L, multiplies, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/negate.h b/include/sqlpp11/operator/negate.h
new file mode 100644
index 00000000..9ce16d0d
--- /dev/null
+++ b/include/sqlpp11/operator/negate.h
@@ -0,0 +1,45 @@
+#pragma once
+
+/*
+Copyright (c) 2017, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <utility>
+
+#include <sqlpp11/arithmetic_expression.h>
+
+namespace sqlpp
+{
+  struct negate
+  {
+    static constexpr auto symbol = "-";
+  };
+
+  template <typename R, typename = check_arithmetic_args<R, R>>
+  constexpr auto operator-(R r) -> unary_arithmetic_expression<divides, R>
+  {
+    return {std::move(r)};
+  }
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/not_equal_to.h b/include/sqlpp11/operator/not_equal_to.h
new file mode 100644
index 00000000..cfed7b05
--- /dev/null
+++ b/include/sqlpp11/operator/not_equal_to.h
@@ -0,0 +1,44 @@
+#pragma once
+
+/*
+Copyright (c) 2017- 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/comparison_expression.h>
+
+namespace sqlpp
+{
+  struct not_equal_to
+  {
+    static constexpr auto symbol = " != ";
+  };
+
+  template <typename L, typename R, typename = check_comparison_args<L, R>>
+  constexpr auto operator!=(L l, R r) -> comparison_expression<L, not_equal_to, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/not_in.h b/include/sqlpp11/operator/not_in.h
new file mode 100644
index 00000000..a789d1d0
--- /dev/null
+++ b/include/sqlpp11/operator/not_in.h
@@ -0,0 +1,60 @@
+#pragma once
+
+/*
+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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <tuple>
+#include <vector>
+
+#include <sqlpp11/in_expression.h>
+
+namespace sqlpp
+{
+  struct operator_not_in
+  {
+    static constexpr auto symbol = " NOT IN ";
+  };
+
+#warning: something.in(select(...)); should be suppported as is
+  template <typename L, typename... Args, typename = check_in_args<L, Args...>>
+  constexpr auto not_in(L l, std::tuple<Args...> args) -> in_expression<L, operator_not_in, std::tuple<Args...>>
+  {
+    return {std::move(l), std::move(args)};
+  }
+
+  template <typename L, typename... Args, typename = check_in_args<L, Args...>>
+  constexpr auto not_in(L l, Args... args) -> in_expression<L, operator_not_in, std::tuple<Args...>>
+  {
+    return {std::move(l), std::make_tuple(std::move(args)...)};
+  }
+
+  template <typename L, typename Arg, typename = check_in_args<L, Arg>>
+  constexpr auto not_in(L l, std::vector<Arg> args) -> in_expression<L, operator_not_in, std::vector<Arg>>
+  {
+    return {std::move(l), std::move(args)};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/order.h b/include/sqlpp11/operator/order.h
new file mode 100644
index 00000000..0e8ba905
--- /dev/null
+++ b/include/sqlpp11/operator/order.h
@@ -0,0 +1,39 @@
+#pragma once
+
+/*
+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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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/sort_order_expression.h>
+
+namespace sqlpp
+{
+  template <typename L, typename = check_sort_order_args<L>>
+  constexpr auto order(L l, sort_order order) -> sort_order_expression<L>
+  {
+    return {l, order};
+  }
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/operator/plus.h b/include/sqlpp11/operator/plus.h
new file mode 100644
index 00000000..d5956acf
--- /dev/null
+++ b/include/sqlpp11/operator/plus.h
@@ -0,0 +1,45 @@
+#pragma once
+
+/*
+Copyright (c) 2016 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <utility>
+
+#include <sqlpp11/arithmetic_expression.h>
+
+namespace sqlpp
+{
+  struct plus
+  {
+    static constexpr auto symbol = " + ";
+  };
+
+  template <typename L, typename R, typename = check_arithmetic_args<L, R>>
+  constexpr auto operator+(L l, R r) -> arithmetic_expression<L, plus, R>
+  {
+    return {std::move(l), std::move(r)};
+  }
+}  // namespace sqlpp
diff --git a/include/sqlpp11/parameter.h b/include/sqlpp11/parameter.h
index 20f27a96..00b16408 100644
--- a/include/sqlpp11/parameter.h
+++ b/include/sqlpp11/parameter.h
@@ -64,7 +64,7 @@ namespace sqlpp
   }
 
   template <typename NamedExpr>
-  auto parameter(const NamedExpr & /*unused*/) -> parameter_t<value_type_of<NamedExpr>, NamedExpr>
+  auto parameter(const NamedExpr & /*unused*/) -> parameter_t<value_type_of_t<NamedExpr>, NamedExpr>
   {
     static_assert(is_selectable_t<NamedExpr>::value, "not a named expression");
     return {};
diff --git a/include/sqlpp11/postgresql/returning_column_list.h b/include/sqlpp11/postgresql/returning_column_list.h
index 11699599..f0d8bcf5 100644
--- a/include/sqlpp11/postgresql/returning_column_list.h
+++ b/include/sqlpp11/postgresql/returning_column_list.h
@@ -60,7 +60,7 @@ namespace sqlpp
       template <typename Column>
       struct returning_traits<Column>
       {
-        using _traits = make_traits<value_type_of<Column>,
+        using _traits = make_traits<value_type_of_t<Column>,
                                     tag::is_returning_column_list,
                                     tag::is_return_value,
                                     tag::is_expression,
diff --git a/include/sqlpp11/schema_qualified_table.h b/include/sqlpp11/schema_qualified_table.h
index a8de5f12..ef95778c 100644
--- a/include/sqlpp11/schema_qualified_table.h
+++ b/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<Table>, tag::is_table>;
+    using _traits = make_traits<value_type_of_t<Table>, tag::is_table>;
 
     using _nodes = detail::type_vector<>;
     using _required_ctes = detail::type_set<>;
diff --git a/include/sqlpp11/select_column_list.h b/include/sqlpp11/select_column_list.h
index bce56ad7..a86b493f 100644
--- a/include/sqlpp11/select_column_list.h
+++ b/include/sqlpp11/select_column_list.h
@@ -55,7 +55,7 @@ namespace sqlpp
     template <typename Column>
     struct select_traits<Column>
     {
-      using _traits = make_traits<value_type_of<remove_optional_t<Column>>,
+      using _traits = make_traits<value_type_of_t<remove_optional_t<Column>>,
                                   tag::is_select_column_list,
                                   tag::is_return_value,
                                   tag::is_expression,
diff --git a/include/sqlpp11/select_pseudo_table.h b/include/sqlpp11/select_pseudo_table.h
index 39c1c474..a2e55658 100644
--- a/include/sqlpp11/select_pseudo_table.h
+++ b/include/sqlpp11/select_pseudo_table.h
@@ -44,9 +44,8 @@ namespace sqlpp
         detail::make_intersect_set_t<required_tables_of<NamedExpr>, typename Select::_used_outer_tables>::size::value >
         0;
 
-    using _traits = make_traits<value_type_of<NamedExpr>,
-                                tag::must_not_insert,
-                                tag::must_not_update,
+#warning: somehow prevent insert...
+    using _traits = make_traits<value_type_of_t<NamedExpr>,
                                 tag_if<tag::can_be_null, _can_be_null or _depends_on_outer_table>>;
   };
 
@@ -59,7 +58,7 @@ namespace sqlpp
 
   template<typename NamedExpr>
   struct select_expression_type<NamedExpr> {
-    using value_t = value_type_of<NamedExpr>;
+    using value_t = value_type_of_t<NamedExpr>;
     static constexpr bool _is_expression = true;
     static constexpr bool _can_be_null = can_be_null_t<NamedExpr>::value;
   };
diff --git a/include/sqlpp11/some.h b/include/sqlpp11/some.h
index 1024f086..b1ab78bc 100644
--- a/include/sqlpp11/some.h
+++ b/include/sqlpp11/some.h
@@ -35,7 +35,7 @@ namespace sqlpp
   template <typename Select>
   struct some_t
   {
-    using _traits = make_traits<value_type_of<Select>, tag::is_multi_expression>;
+    using _traits = make_traits<value_type_of_t<Select>, tag::is_multi_expression>;
     using _nodes = detail::type_vector<Select>;
 
     some_t(Select select) : _select(select)
diff --git a/include/sqlpp11/sort_order_expression.h b/include/sqlpp11/sort_order_expression.h
new file mode 100644
index 00000000..7bf06343
--- /dev/null
+++ b/include/sqlpp11/sort_order_expression.h
@@ -0,0 +1,81 @@
+#pragma once
+
+/*
+Copyright (c) 2017 - 2018, 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:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. 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 <type_traits>
+
+namespace sqlpp
+{
+  enum class sort_order
+  {
+    asc,
+    desc,
+  };
+
+  template <typename L>
+  struct sort_order_expression
+  {
+    L l;
+    sort_order order;
+  };
+
+  template <typename L>
+  using check_sort_order_args = std::enable_if_t<values_are_comparable<L, L>::value>;
+
+  /*
+  template <typename L>
+  struct nodes_of<sort_order_t<L>>
+  {
+    using type = type_vector<L>;
+  };
+
+  template <typename L>
+  constexpr auto requires_braces_v<sort_order_t<L>> = false;
+
+  template <typename L>
+  constexpr auto is_sort_order_v<sort_order_t<L>> = true;
+
+  template <typename Context>
+  [[nodiscard]] auto to_sql_string(Context& context, const sort_order& t)
+  {
+    switch (t)
+    {
+      case sort_order::asc:
+        return std::string(" ASC");
+      case sort_order::desc:
+        return std::string(" DESC");
+    }
+  }
+
+  template <typename Context, typename L>
+  [[nodiscard]] auto to_sql_string(Context& context, const sort_order_t<L>& t)
+  {
+    return to_sql_string(context, embrace(t.l)) + to_sql_string(context, t.order);
+  }
+  */
+
+}  // namespace sqlpp
diff --git a/include/sqlpp11/sqlpp11.h b/include/sqlpp11/sqlpp11.h
index 274aebb0..6fd9b436 100644
--- a/include/sqlpp11/sqlpp11.h
+++ b/include/sqlpp11/sqlpp11.h
@@ -33,6 +33,7 @@
 #include <sqlpp11/update.h>
 #include <sqlpp11/select.h>
 #include <sqlpp11/functions.h>
+#include <sqlpp11/operator.h>
 #include <sqlpp11/transaction.h>
 #include <sqlpp11/without_table_check.h>
 #include <sqlpp11/schema_qualified_table.h>
diff --git a/include/sqlpp11/statement.h b/include/sqlpp11/statement.h
index 956d3c9b..d9036a91 100644
--- a/include/sqlpp11/statement.h
+++ b/include/sqlpp11/statement.h
@@ -132,7 +132,7 @@ namespace sqlpp
           typename std::conditional<is_any_policy_missing<Policies...>(),
                                     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
-                                    value_type_of<_result_type_provider>>::type;
+                                    value_type_of_t<_result_type_provider>>::type;
 
       using _traits =
           make_traits<_value_type, tag_if<tag::is_expression, not std::is_same<_value_type, no_value_t>::value>>;
@@ -151,12 +151,19 @@ namespace sqlpp
       using _parameter_check = typename std::
           conditional<detail::type_vector_size<_parameters>::value == 0, consistent_t, assert_no_parameters_t>::type;
     };
+
   }  // namespace detail
 
+  template <typename... Policies>
+  struct value_type_of<detail::statement_policies_t<Policies...>>
+  {
+    using type = typename detail::statement_policies_t<Policies...>::_value_type;
+  };
+
   template <typename... Policies>
   struct statement_t : public Policies::template _base_t<detail::statement_policies_t<Policies...>>...,
                        public expression_operators<statement_t<Policies...>,
-                                                   value_type_of<detail::statement_policies_t<Policies...>>>,
+                                                   value_type_of_t<detail::statement_policies_t<Policies...>>>,
                        public detail::statement_policies_t<Policies...>::_result_methods_t
   {
     using _policies_t = typename detail::statement_policies_t<Policies...>;
@@ -185,7 +192,7 @@ namespace sqlpp
     using _result_methods_t = typename _result_type_provider::template _result_methods_t<Composite>;
 
     using _traits =
-        make_traits<value_type_of<_policies_t>,
+        make_traits<value_type_of_t<_policies_t>,
                     tag::is_statement,
                     tag_if<tag::is_select, logic::any_t<is_select_t<Policies>::value...>::value>,
                     tag_if<tag::is_expression, is_expression_t<_policies_t>::value>,
diff --git a/include/sqlpp11/table.h b/include/sqlpp11/table.h
index cb78cd81..c8369fa2 100644
--- a/include/sqlpp11/table.h
+++ b/include/sqlpp11/table.h
@@ -48,8 +48,6 @@ namespace sqlpp
     using _provided_tables = detail::type_set<Table>;
 
     static_assert(sizeof...(ColumnSpec) > 0, "at least one column required per table");
-    using _required_insert_columns =
-        typename detail::make_type_set_if<require_insert_t, column_t<Table, ColumnSpec>...>::type;
     using _column_tuple_t = std::tuple<column_t<Table, ColumnSpec>...>;
     template <typename AliasProvider, typename T>
     using _foreign_table_alias_t = table_alias_t<AliasProvider, T, ColumnSpec...>;
diff --git a/include/sqlpp11/table_alias.h b/include/sqlpp11/table_alias.h
index ebc97d6d..4d3bfda6 100644
--- a/include/sqlpp11/table_alias.h
+++ b/include/sqlpp11/table_alias.h
@@ -41,7 +41,7 @@ namespace sqlpp
   template <typename AliasProvider, typename Table, typename... ColumnSpec>
   struct table_alias_t : public ColumnSpec::_alias_t::template _member_t<column_t<AliasProvider, ColumnSpec>>...
   {
-    using _traits = make_traits<value_type_of<Table>,
+    using _traits = make_traits<value_type_of_t<Table>,
                                 tag::is_table,
                                 tag::is_alias,
                                 tag_if<tag::can_be_null, can_be_null_t<Table>::value>,
diff --git a/include/sqlpp11/type_traits.h b/include/sqlpp11/type_traits.h
index f67b5458..c8bc0281 100644
--- a/include/sqlpp11/type_traits.h
+++ b/include/sqlpp11/type_traits.h
@@ -26,10 +26,15 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <type_traits>
+#include <cstdint>
 #include <tuple>
+#include <type_traits>
+#include <vector>
 
+#include <sqlpp11/chrono.h>
 #include <sqlpp11/compat/optional.h>
+#include <sqlpp11/compat/string_view.h>
+#include <sqlpp11/compat/span.h>
 #include <sqlpp11/consistent.h>
 #include <sqlpp11/portable_static_assert.h>
 #include <sqlpp11/detail/type_vector.h>
@@ -49,6 +54,11 @@ namespace sqlpp
   {
   };
 
+  template <>
+  struct is_optional<sqlpp::compat::nullopt_t> : public std::true_type
+  {
+  };
+
   template <typename T>
   struct remove_optional
   {
@@ -61,6 +71,9 @@ namespace sqlpp
     using type = T;
   };
 
+  template <typename T>
+  using remove_optional_t = typename remove_optional<T>::type;
+
   template <typename T>
   const T& get_value(const T& t)
   {
@@ -85,26 +98,26 @@ namespace sqlpp
     return t.has_value();
   }
 
-  template <typename T>
-  using remove_optional_t = typename remove_optional<T>::type;
-
   struct no_value_t;
-  namespace detail
-  {
-    template <typename T, typename Enable = void>
-    struct value_type_of_impl
-    {
-      using type = no_value_t;
-    };
 
-    template <typename T>
-    struct value_type_of_impl<T, detail::void_t<typename T::_traits::_value_type>>
-    {
-      using type = typename T::_traits::_value_type;
-    };
-  }  // namespace detail
+  // This requires specializations for anything that has a value, like a column or a boolean expression
   template <typename T>
-  using value_type_of = typename detail::value_type_of_impl<T>::type;
+  struct value_type_of
+  {
+    using type = no_value_t;
+  };
+
+  template <typename T>
+  using value_type_of_t = typename value_type_of<T>::type;
+
+  template<typename T>
+  struct value_type_of<sqlpp::compat::optional<T>>
+  {
+    using type = sqlpp::compat::optional<value_type_of_t<remove_optional_t<T>>>;
+  };
+
+  template <typename T>
+  struct has_value_type : public std::integral_constant<bool, not std::is_same<value_type_of_t<T>, no_value_t>::value> {};
 
   template <typename T>
   struct is_not_cpp_bool_t
@@ -112,42 +125,280 @@ namespace sqlpp
     static constexpr bool value = not std::is_same<T, bool>::value;
   };
 
-  // data types
-  struct blob;
-  template <typename T>
-  using is_blob_t = std::is_same<value_type_of<T>, blob>;
-
+  //
   struct boolean;
-  template <typename T>
-  using is_boolean_t = std::is_same<value_type_of<T>, boolean>;
+  template<>
+  struct value_type_of<bool> { using type = boolean; };
 
-  struct day_point;
-  template <typename T>
-  using is_day_point_t = std::is_same<value_type_of<T>, day_point>;
+  struct integral;
+  template<>
+  struct value_type_of<int8_t> { using type = integral; };
+  template<>
+  struct value_type_of<int16_t> { using type = integral; };
+  template<>
+  struct value_type_of<int32_t> { using type = integral; };
+  template<>
+  struct value_type_of<int64_t> { using type = integral; };
+
+  struct unsigned_integral;
+  template<>
+  struct value_type_of<uint8_t> { using type = unsigned_integral; };
+  template<>
+  struct value_type_of<uint16_t> { using type = unsigned_integral; };
+  template<>
+  struct value_type_of<uint32_t> { using type = unsigned_integral; };
+  template<>
+  struct value_type_of<uint64_t> { using type = unsigned_integral; };
 
   struct floating_point;
+  template<>
+  struct value_type_of<float> { using type = floating_point; };
+  template<>
+  struct value_type_of<double> { using type = floating_point; };
+
+  struct text;
+  template <>
+  struct value_type_of<char> { using type = text; };
+  template <>
+  struct value_type_of<const char*> { using type = text; };
+  template <>
+  struct value_type_of<std::string> { using type = text; };
+  template <>
+  struct value_type_of<sqlpp::compat::string_view> { using type = text; };
+
+  /////////////////
+  struct blob;
+  template <>
+  struct value_type_of<std::vector<std::uint8_t>> { using type = blob; };
+
+  template <>
+  struct value_type_of<sqlpp::compat::span<std::uint8_t>> { using type = blob; };
+
+  struct day_point;
+  template <>
+  struct value_type_of<std::chrono::time_point<std::chrono::system_clock, sqlpp::chrono::days>> { using type = day_point; };
+
+  struct time_of_day;
+  template <typename Rep, typename Period>
+  struct value_type_of<std::chrono::duration<Rep, Period>> { using type = time_of_day; };
+
+  struct time_point;
+  template <typename Period>
+  struct value_type_of<std::chrono::time_point<std::chrono::system_clock, Period>> { using type = time_point; };
+  /////////////////
+
+
+
+
   template <typename T>
-  using is_floating_point_t = std::is_same<value_type_of<T>, floating_point>;
+  struct is_boolean : public std::is_same<T, bool>
+  {
+  };
+
+  template <>
+  struct is_boolean<boolean> : public std::true_type {
+  };
+
+  template <>
+  struct is_boolean<sqlpp::compat::nullopt_t> : public std::true_type {
+  };
+
+  template <typename T>
+  struct has_boolean_value : public std::integral_constant<bool,
+                                                           is_boolean<remove_optional_t<T>>::value or
+                                                               is_boolean<remove_optional_t<value_type_of_t<T>>>::value>
+  {
+  };
 
   struct integral;
   template <typename T>
-  using is_integral_t = std::is_same<value_type_of<T>, integral>;
+  struct is_integral : public std::is_integral<T>{};
+
+  template <>
+  struct is_integral<char> : public std::false_type  // char is text
+  {
+  };
+
+  template <>
+  struct is_integral<bool> : public std::false_type  // bool is boolean
+  {
+  };
+
+  template <>
+  struct is_integral<sqlpp::compat::nullopt_t> : public std::true_type{};
+
+  template <>
+  struct is_integral<integral> : public std::true_type{};
 
-  struct unsigned_integral;
   template <typename T>
-  using is_unsigned_integral_t = std::is_same<value_type_of<T>, unsigned_integral>;
+  struct has_integral_value
+      : public std::integral_constant<bool,
+                                      is_integral<remove_optional_t<T>>::value or
+                                          is_integral<remove_optional_t<value_type_of_t<T>>>::value>
+  {
+  };
+
+  template <typename T>
+  struct is_numeric : public std::integral_constant<bool, is_integral<T>::value or std::is_floating_point<T>::value>{};
+
+  template <>
+  struct is_numeric<sqlpp::compat::nullopt_t> : public std::true_type{};
+
+  template <typename T>
+  struct has_numeric_value : public std::integral_constant<bool,
+      is_numeric<remove_optional_t<T>>::value or is_numeric<remove_optional_t<value_type_of_t<T>>>::value>{};
 
   struct text;
   template <typename T>
-  using is_text_t = std::is_same<value_type_of<T>, text>;
+  struct is_text : public std::false_type {};
+
+  template <>
+  struct is_text<text> : public std::true_type {};
+
+  template <>
+  struct is_text<char> : public std::true_type {};
+
+  template <>
+  struct is_text<const char*> : public std::true_type {};
+
+  template <>
+  struct is_text<std::string> : public std::true_type {};
+
+  template <>
+  struct is_text<sqlpp::compat::string_view> : public std::true_type {};
+
+  template <>
+  struct is_text<sqlpp::compat::nullopt_t> : public std::true_type {};
+
+  template <typename T>
+  struct has_text_value : public std::integral_constant<bool,
+                                                        is_text<remove_optional_t<T>>::value or
+                                                            is_text<remove_optional_t<value_type_of_t<T>>>::value>{};
+
+  struct blob;
+  template <typename T>
+  struct is_blob : public std::false_type {};
+
+  template <>
+  struct is_blob<blob> : public std::true_type {};
+
+  template <>
+  struct is_blob<std::vector<std::uint8_t>> : public std::true_type {};
+
+  template <>
+  struct is_blob<sqlpp::compat::span<std::uint8_t>> : public std::true_type {};
+
+  template <>
+  struct is_blob<sqlpp::compat::nullopt_t> : public std::true_type {};
+
+  template <typename T>
+  struct has_blob_value : public std::integral_constant<bool,
+                                                        is_blob<remove_optional_t<T>>::value or
+                                                            is_blob<remove_optional_t<value_type_of_t<T>>>::value>{};
+
+  struct day_point;
+  template <typename T>
+  struct is_day_point : public std::false_type {};
+
+  template <>
+  struct is_day_point<day_point> : public std::true_type {};
+
+  template <>
+  struct is_day_point<std::chrono::time_point<std::chrono::system_clock, sqlpp::chrono::days>> : public std::true_type {};
+
+  template <>
+  struct is_day_point<sqlpp::compat::nullopt_t> : public std::true_type {};
+
+  template <typename T>
+  struct has_day_point_value : public std::integral_constant<bool,
+                                                        is_day_point<remove_optional_t<T>>::value or
+                                                            is_day_point<remove_optional_t<value_type_of_t<T>>>::value>{};
 
   struct time_of_day;
   template <typename T>
-  using is_time_of_day_t = std::is_same<value_type_of<T>, time_of_day>;
+  struct is_time_of_day : public std::false_type {};
+
+  template <>
+  struct is_time_of_day<time_of_day> : public std::true_type {};
+
+  template <typename Rep, typename Period>
+  struct is_time_of_day<std::chrono::duration<Rep, Period>> : public std::true_type {};
+
+  template <>
+  struct is_time_of_day<sqlpp::compat::nullopt_t> : public std::true_type {};
+
+  template <typename T>
+  struct has_time_of_day_value : public std::integral_constant<bool,
+                                                        is_time_of_day<remove_optional_t<T>>::value or
+                                                            is_time_of_day<remove_optional_t<value_type_of_t<T>>>::value>{};
 
   struct time_point;
   template <typename T>
-  using is_time_point_t = std::is_same<value_type_of<T>, time_point>;
+  struct is_time_point : public std::false_type {};
+
+  template <>
+  struct is_time_point<time_point> : public std::true_type {};
+
+  template <typename Period>
+  struct is_time_point<std::chrono::time_point<std::chrono::system_clock, Period>> : public std::true_type {};
+
+  template <>
+  struct is_time_point<sqlpp::compat::nullopt_t> : public std::true_type {};
+
+  template <typename T>
+  struct has_time_point_value : public std::integral_constant<bool,
+                                                        is_time_point<remove_optional_t<T>>::value or
+                                                            is_time_point<remove_optional_t<value_type_of_t<T>>>::value>{};
+
+#warning: Need to add float and unsigned traits?
+  template <typename L, typename R>
+  struct values_are_comparable
+      : public std::integral_constant<bool,
+                                      (has_blob_value<L>::value and has_blob_value<R>::value) or
+                                          (has_boolean_value<L>::value and has_boolean_value<R>::value) or
+                                          (has_day_point_value<L>::value and has_day_point_value<R>::value) or
+                                          (has_numeric_value<L>::value and has_numeric_value<R>::value) or
+                                          (has_text_value<L>::value and has_text_value<R>::value) or
+                                          (has_time_of_day_value<L>::value and has_time_of_day_value<R>::value) or
+                                          (has_time_point_value<L>::value and has_time_point_value<R>::value)>
+  {
+  };
+
+  // data types
+  struct blob;
+  template <typename T>
+  using is_blob_t = std::is_same<value_type_of_t<T>, blob>;
+
+  template <typename T>
+  using is_boolean_t = std::is_same<value_type_of_t<T>, boolean>;
+
+  struct day_point;
+  template <typename T>
+  using is_day_point_t = std::is_same<value_type_of_t<T>, day_point>;
+
+  struct floating_point;
+  template <typename T>
+  using is_floating_point_t = std::is_same<value_type_of_t<T>, floating_point>;
+
+  struct integral;
+  template <typename T>
+  using is_integral_t = std::is_same<value_type_of_t<T>, integral>;
+
+  struct unsigned_integral;
+  template <typename T>
+  using is_unsigned_integral_t = std::is_same<value_type_of_t<T>, unsigned_integral>;
+
+  struct text;
+  template <typename T>
+  using is_text_t = std::is_same<value_type_of_t<T>, text>;
+
+  struct time_of_day;
+  template <typename T>
+  using is_time_of_day_t = std::is_same<value_type_of_t<T>, time_of_day>;
+
+  struct time_point;
+  template <typename T>
+  using is_time_point_t = std::is_same<value_type_of_t<T>, time_point>;
 
   // joined data type
   template <typename T>
@@ -220,9 +471,8 @@ namespace sqlpp
   SQLPP_VALUE_TRAIT_GENERATOR(is_union_flag)
   SQLPP_VALUE_TRAIT_GENERATOR(is_result_field)
 
-  SQLPP_VALUE_TRAIT_GENERATOR(must_not_insert)
-  SQLPP_VALUE_TRAIT_GENERATOR(must_not_update)
-  SQLPP_VALUE_TRAIT_GENERATOR(require_insert)
+#warning Document loss of must_not_insert/update and require_insert (and new has_default)
+  SQLPP_VALUE_TRAIT_GENERATOR(has_default)
 
   SQLPP_VALUE_TRAIT_GENERATOR(is_statement)
   SQLPP_VALUE_TRAIT_GENERATOR(is_prepared_statement)
@@ -277,7 +527,7 @@ namespace sqlpp
       typename std::conditional<std::is_same<Database, void>::value, std::false_type, std::true_type>::type;
 
   template <typename T>
-  using cpp_value_type_of = typename value_type_of<T>::_cpp_value_type;
+  using cpp_value_type_of_t = typename value_type_of_t<T>::_cpp_value_type;
 
   namespace detail
   {
@@ -468,6 +718,12 @@ namespace sqlpp
   template <typename T>
   using name_of = typename T::_alias_t::_name_t;
 
+  template<typename T, typename = void>
+  struct has_name : public std::false_type {};
+
+  template<typename T>
+  struct has_name<T, typename T::_alias_t> : public std::true_type {};
+
   template <typename ValueType, typename... Tags>
   struct make_traits
   {
diff --git a/include/sqlpp11/update_list.h b/include/sqlpp11/update_list.h
index fe55b630..7ba9959b 100644
--- a/include/sqlpp11/update_list.h
+++ b/include/sqlpp11/update_list.h
@@ -89,23 +89,12 @@ namespace sqlpp
                                "set() contains assignments for columns from more than one table");
   SQLPP_PORTABLE_STATIC_ASSERT(assert_update_set_count_args_t, "at least one assignment expression required in set()");
 
-  namespace detail
-  {
-    template <typename Assignment>
-    struct lhs_must_not_update
-    {
-      static constexpr auto value = detail::must_not_update_impl<typename lhs<Assignment>::type>::type::value;
-    };
-  }  // namespace detail
-
   template <typename... Assignments>
   using check_update_set_t = static_combined_check_t<
       static_check_t<logic::all_t<detail::is_assignment_impl<Assignments>::type::value...>::value,
                      assert_update_set_assignments_t>,
       static_check_t<not detail::has_duplicates<typename lhs<Assignments>::type...>::value,
                      assert_update_set_no_duplicates_t>,
-      static_check_t<logic::none_t<detail::lhs_must_not_update<Assignments>::value...>::value,
-                     assert_update_set_allowed_t>,
       static_check_t<sizeof...(Assignments) == 0 or detail::make_joined_set_t<required_tables_of<
                                                         typename lhs<Assignments>::type>...>::size::value == 1,
                      assert_update_set_single_table_t>>;
diff --git a/include/sqlpp11/value.h b/include/sqlpp11/value.h
index 35caada7..4c282f97 100644
--- a/include/sqlpp11/value.h
+++ b/include/sqlpp11/value.h
@@ -33,16 +33,28 @@
 namespace sqlpp
 {
   template <typename T>
-  struct value_t : public wrap_operand_t<T>, public expression_operators<value_t<T>, value_type_of<wrap_operand_t<T>>>
+  struct value_t
   {
-    using _base_t = wrap_operand_t<T>;
-    using _base_t::_base_t;
+    template <typename alias_provider>
+    expression_alias_t<value_t, alias_provider> as(const alias_provider& /*unused*/) const
+    {
+      return {*this};
+    }
+
+    T _value;
   };
+  template<typename T>
+  struct value_type_of<value_t<T>>
+  {
+    using type = value_type_of_t<T>;
+  };
+
   template <typename T>
+  using check_value_arg = std::enable_if_t<not std::is_same<value_type_of_t<T>, no_value_t>::value and values_are_comparable<T, T>::value>;
+
+  template <typename T, typename = check_value_arg<T>>
   auto value(T t) -> value_t<T>
   {
-    static_assert(is_wrapped_value_t<wrap_operand_t<T>>::value,
-                  "value() is to be called with non-sql-type like int, or string");
-    return {t};
+    return {std::move(t)};
   }
 }  // namespace sqlpp
diff --git a/include/sqlpp11/value_or_null.h b/include/sqlpp11/value_or_null.h
index 7bb1aae1..2d877c42 100644
--- a/include/sqlpp11/value_or_null.h
+++ b/include/sqlpp11/value_or_null.h
@@ -68,7 +68,7 @@ namespace sqlpp
   }
 
   template <typename T>
-  auto value_or_null(T t) -> value_or_null_t<value_type_of<wrap_operand_t<T>>>
+  auto value_or_null(T t) -> value_or_null_t<value_type_of_t<wrap_operand_t<T>>>
   {
     static_assert(is_wrapped_value_t<wrap_operand_t<T>>::value,
                   "value_or_null() is to be called with non-sql-type like int, or string or null");
diff --git a/include/sqlpp11/value_type.h b/include/sqlpp11/value_type.h
index 7fa338c2..bb2b4517 100644
--- a/include/sqlpp11/value_type.h
+++ b/include/sqlpp11/value_type.h
@@ -32,5 +32,5 @@
 namespace sqlpp
 {
   template <typename T>
-  using value_type_t = value_type_of<wrap_operand_t<T>>;
+  using value_type_t = value_type_of_t<wrap_operand_t<T>>;
 }  // namespace sqlpp
diff --git a/scripts/ddl2cpp b/scripts/ddl2cpp
index 0d476a4b..7e154366 100755
--- a/scripts/ddl2cpp
+++ b/scripts/ddl2cpp
@@ -703,8 +703,8 @@ def createHeader():
                 )
                 print("You can disable this warning using -no-timestamp-warning")
                 noTimestampWarning = True
-            traitslist = ["sqlpp::" + columnType]
-            columnCanBeNull = not column.notNull
+            traitslist = ["::sqlpp::" + columnType]
+            columnCanBeNull = not column.notNull and not column.isPrimaryKey
             print("    struct " + columnClass, file=header)
             print("    {", file=header)
             print("      struct _alias_t", file=header)
@@ -716,7 +716,7 @@ def createHeader():
                 file=header,
             )
             print(
-                "        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;",
+                "        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;",
                 file=header,
             )
             print("        template<typename T>", file=header)
@@ -735,21 +735,17 @@ def createHeader():
             )
             print("          };", file=header)
             print("      };", file=header)
-            requireInsert = True
             hasAutoValue = column.hasAutoValue or (autoId and sqlColumnName == "id")
-            if hasAutoValue:
-                traitslist.append("sqlpp::tag::must_not_insert")
-                traitslist.append("sqlpp::tag::must_not_update")
-                requireInsert = False
-            if not column.notNull and not column.isPrimaryKey:
-                traitslist.append("sqlpp::tag::can_be_null")
-                requireInsert = False
-            if column.hasDefaultValue:
-                requireInsert = False
-            if requireInsert:
-                traitslist.append("sqlpp::tag::require_insert")
+            if columnCanBeNull:
+                traitslist.append("::sqlpp::tag::can_be_null")
+            if column.hasDefaultValue or hasAutoValue or columnCanBeNull:
+                traitslist.append("::sqlpp::tag::has_default")
+            if columnCanBeNull:
+                print("      using value_type = ::sqlpp::compat::optional<::sqlpp::" + columnType + ">;", file=header)
+            else:
+                print("      using value_type = ::sqlpp::" + columnType + ";", file=header)
             print(
-                "      using _traits = sqlpp::make_traits<"
+                "      using _traits = ::sqlpp::make_traits<"
                 + ", ".join(traitslist)
                 + ">;",
                 file=header,
@@ -761,7 +757,7 @@ def createHeader():
         print(
             "  struct "
             + tableClass
-            + ": sqlpp::table_t<"
+            + ": ::sqlpp::table_t<"
             + tableTemplateParameters
             + ">",
             file=header,
@@ -774,7 +770,7 @@ def createHeader():
             file=header,
         )
         print(
-            "      using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;",
+            "      using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;",
             file=header,
         )
         print("      template<typename T>", file=header)
diff --git a/tests/core/types/result_row.cpp b/tests/core/types/result_row.cpp
index 0b4d8e61..e0da2af1 100644
--- a/tests/core/types/result_row.cpp
+++ b/tests/core/types/result_row.cpp
@@ -99,20 +99,44 @@ int main()
   }
 
   // Select value and optional value.
-  sqlpp::value(7);
-  /*
   for (const auto& row : db(select(sqlpp::value(7).as(sqlpp::alias::a),
                                    sqlpp::value(sqlpp::compat::optional<int>(7)).as(sqlpp::alias::b))))
-                                   */
   {
-    /*
     static_assert(is_same_type<decltype(row.a), int64_t>(), "");
-    static_assert(is_same_type<decltype(row.a), sqlpp::compat::optional<int64_t>>(), "");
-    static_assert(is_same_type<decltype(row.textN), sqlpp::compat::optional<sqlpp::compat::string_view>>(), "");
-    static_assert(is_same_type<decltype(row.b), sqlpp::compat::optional<sqlpp::compat::string_view>>(), "");
-    */
+    static_assert(is_same_type<decltype(row.b), sqlpp::compat::optional<int64_t>>(), "");
   }
 
+  static_assert(sqlpp::has_boolean_value<bool>::value, "");
+  static_assert(sqlpp::has_boolean_value<decltype(bar.boolNn)>::value, "");
+  static_assert(sqlpp::has_text_value<decltype(bar.textN)>::value, "");
+  static_assert(sqlpp::has_text_value<std::string>::value, "");
+  static_assert(sqlpp::has_numeric_value<int>::value, "");
+  static_assert(sqlpp::has_numeric_value<decltype(bar.intN)>::value, "");
+#warning: Need to implement value_type_of for expressions
+  //static_assert(sqlpp::has_boolean_value<decltype(!bar.boolNn)>::value, "");
+  //static_assert(sqlpp::has_boolean_value<decltype(bar.boolNn and bar.boolNn)>::value, "");
+#if 0
+  !bar.boolNn;
+  (bar.boolNn and bar.boolNn).hansi;
+  like(bar.textN, "hansi").berti;
+
+#endif
+  (bar.textN == "hansi").berti;
+  (-bar.intN).berti;
+  (bar.intN + 7).berti;
+  (bar.intN << 7).berti;
+  assign(bar.intN, sqlpp::compat::nullopt).berti;
+#warning: This is not the real thing yet
+  bar.intN.as(bar.textN).berti;
+
+  in(bar.intN, 7, 8, 9).berti;
+  in(bar.intN, std::vector<int>{7, 8, 9}).berti;
+  max(bar.intN);
+  sqlpp::max(7);
+
+
+#warning: No magic for NULL in operators, e.g. comparison. It might therefore be reasonable to disallow comparison with optoinal values? But then again, columns can also be NULL, failing to compare to anything. In any case, do not translate `a == nullopt` to `a IS NULL`. Same for parameters.
+
 #if 0
 
 
diff --git a/tests/core/usage/Sample.h b/tests/core/usage/Sample.h
index a6cb467a..890724e5 100644
--- a/tests/core/usage/Sample.h
+++ b/tests/core/usage/Sample.h
@@ -1,6 +1,6 @@
 #pragma once
 
-// generated by ./scripts/ddl2cpp -with-table-creation-helper tests/core/usage/sample.sql tests/core/usage/Sample test
+// generated by ./scripts/ddl2cpp -auto-id tests/core/usage/sample.sql tests/core/usage/Sample test
 
 #include <sqlpp11/table.h>
 #include <sqlpp11/data_types.h>
@@ -8,21 +8,6 @@
 
 namespace test
 {
-  template<typename Db>
-  void createTabFoo(Db& db)
-  {
-    db.execute(R"+++(DROP TABLE IF EXISTS tab_foo)+++");
-    db.execute(R"+++(CREATE TABLE tab_foo
-(
-        id bigint AUTO_INCREMENT PRIMARY KEY,
-        text_nn_d varchar(255) NOT NULL DEFAULT "",
-        int_n bigint,
-        double_n double,
-        u_int_n bigint UNSIGNED,
-        blob_n BLOB
-))+++");
-  }
-
   namespace TabFoo_
   {
     struct Id
@@ -30,7 +15,7 @@ namespace test
       struct _alias_t
       {
         static constexpr const char _literal[] =  "id";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -39,14 +24,15 @@ namespace test
             const T& operator()() const { return id; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::integer, sqlpp::tag::must_not_insert, sqlpp::tag::must_not_update>;
+      using value_type = ::sqlpp::integer;
+      using _traits = ::sqlpp::make_traits<::sqlpp::integer, ::sqlpp::tag::has_default>;
     };
     struct TextNnD
     {
       struct _alias_t
       {
         static constexpr const char _literal[] =  "text_nn_d";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -55,14 +41,15 @@ namespace test
             const T& operator()() const { return textNnD; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::text>;
+      using value_type = ::sqlpp::text;
+      using _traits = ::sqlpp::make_traits<::sqlpp::text, ::sqlpp::tag::has_default>;
     };
     struct IntN
     {
       struct _alias_t
       {
         static constexpr const char _literal[] =  "int_n";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -71,14 +58,15 @@ namespace test
             const T& operator()() const { return intN; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::integer, sqlpp::tag::can_be_null>;
+      using value_type = ::sqlpp::compat::optional<::sqlpp::integer>;
+      using _traits = ::sqlpp::make_traits<::sqlpp::integer, ::sqlpp::tag::can_be_null, ::sqlpp::tag::has_default>;
     };
     struct DoubleN
     {
       struct _alias_t
       {
         static constexpr const char _literal[] =  "double_n";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -87,14 +75,15 @@ namespace test
             const T& operator()() const { return doubleN; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::floating_point, sqlpp::tag::can_be_null>;
+      using value_type = ::sqlpp::compat::optional<::sqlpp::floating_point>;
+      using _traits = ::sqlpp::make_traits<::sqlpp::floating_point, ::sqlpp::tag::can_be_null, ::sqlpp::tag::has_default>;
     };
     struct UIntN
     {
       struct _alias_t
       {
         static constexpr const char _literal[] =  "u_int_n";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -103,14 +92,15 @@ namespace test
             const T& operator()() const { return uIntN; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::integer_unsigned, sqlpp::tag::can_be_null>;
+      using value_type = ::sqlpp::compat::optional<::sqlpp::integer_unsigned>;
+      using _traits = ::sqlpp::make_traits<::sqlpp::integer_unsigned, ::sqlpp::tag::can_be_null, ::sqlpp::tag::has_default>;
     };
     struct BlobN
     {
       struct _alias_t
       {
         static constexpr const char _literal[] =  "blob_n";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -119,11 +109,12 @@ namespace test
             const T& operator()() const { return blobN; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::blob, sqlpp::tag::can_be_null>;
+      using value_type = ::sqlpp::compat::optional<::sqlpp::blob>;
+      using _traits = ::sqlpp::make_traits<::sqlpp::blob, ::sqlpp::tag::can_be_null, ::sqlpp::tag::has_default>;
     };
   } // namespace TabFoo_
 
-  struct TabFoo: sqlpp::table_t<TabFoo,
+  struct TabFoo: ::sqlpp::table_t<TabFoo,
                TabFoo_::Id,
                TabFoo_::TextNnD,
                TabFoo_::IntN,
@@ -134,7 +125,7 @@ namespace test
     struct _alias_t
     {
       static constexpr const char _literal[] =  "tab_foo";
-      using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+      using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
       template<typename T>
       struct _member_t
       {
@@ -144,19 +135,6 @@ namespace test
       };
     };
   };
-  template<typename Db>
-  void createTabBar(Db& db)
-  {
-    db.execute(R"+++(DROP TABLE IF EXISTS tab_bar)+++");
-    db.execute(R"+++(CREATE TABLE tab_bar
-(
-        id bigint AUTO_INCREMENT PRIMARY KEY,
-        text_n varchar(255) NULL DEFAULT "",
-        bool_nn bool NOT NULL,
-        int_n int
-))+++");
-  }
-
   namespace TabBar_
   {
     struct Id
@@ -164,7 +142,7 @@ namespace test
       struct _alias_t
       {
         static constexpr const char _literal[] =  "id";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -173,14 +151,15 @@ namespace test
             const T& operator()() const { return id; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::integer, sqlpp::tag::must_not_insert, sqlpp::tag::must_not_update>;
+      using value_type = ::sqlpp::integer;
+      using _traits = ::sqlpp::make_traits<::sqlpp::integer, ::sqlpp::tag::has_default>;
     };
     struct TextN
     {
       struct _alias_t
       {
         static constexpr const char _literal[] =  "text_n";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -189,14 +168,15 @@ namespace test
             const T& operator()() const { return textN; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::text, sqlpp::tag::can_be_null>;
+      using value_type = ::sqlpp::compat::optional<::sqlpp::text>;
+      using _traits = ::sqlpp::make_traits<::sqlpp::text, ::sqlpp::tag::can_be_null, ::sqlpp::tag::has_default>;
     };
     struct BoolNn
     {
       struct _alias_t
       {
         static constexpr const char _literal[] =  "bool_nn";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -205,14 +185,15 @@ namespace test
             const T& operator()() const { return boolNn; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::boolean, sqlpp::tag::require_insert>;
+      using value_type = ::sqlpp::boolean;
+      using _traits = ::sqlpp::make_traits<::sqlpp::boolean>;
     };
     struct IntN
     {
       struct _alias_t
       {
         static constexpr const char _literal[] =  "int_n";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -221,11 +202,12 @@ namespace test
             const T& operator()() const { return intN; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::integer, sqlpp::tag::can_be_null>;
+      using value_type = ::sqlpp::compat::optional<::sqlpp::integer>;
+      using _traits = ::sqlpp::make_traits<::sqlpp::integer, ::sqlpp::tag::can_be_null, ::sqlpp::tag::has_default>;
     };
   } // namespace TabBar_
 
-  struct TabBar: sqlpp::table_t<TabBar,
+  struct TabBar: ::sqlpp::table_t<TabBar,
                TabBar_::Id,
                TabBar_::TextN,
                TabBar_::BoolNn,
@@ -234,7 +216,7 @@ namespace test
     struct _alias_t
     {
       static constexpr const char _literal[] =  "tab_bar";
-      using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+      using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
       template<typename T>
       struct _member_t
       {
@@ -244,19 +226,6 @@ namespace test
       };
     };
   };
-  template<typename Db>
-  void createTabDateTime(Db& db)
-  {
-    db.execute(R"+++(DROP TABLE IF EXISTS tab_date_time)+++");
-    db.execute(R"+++(CREATE TABLE tab_date_time
-(
-        id bigint AUTO_INCREMENT PRIMARY KEY,
-        day_point_n date,
-        time_point_n datetime,
-        time_of_day_n time
-))+++");
-  }
-
   namespace TabDateTime_
   {
     struct Id
@@ -264,7 +233,7 @@ namespace test
       struct _alias_t
       {
         static constexpr const char _literal[] =  "id";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -273,14 +242,15 @@ namespace test
             const T& operator()() const { return id; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::integer, sqlpp::tag::must_not_insert, sqlpp::tag::must_not_update>;
+      using value_type = ::sqlpp::integer;
+      using _traits = ::sqlpp::make_traits<::sqlpp::integer, ::sqlpp::tag::has_default>;
     };
     struct DayPointN
     {
       struct _alias_t
       {
         static constexpr const char _literal[] =  "day_point_n";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -289,14 +259,15 @@ namespace test
             const T& operator()() const { return dayPointN; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::day_point, sqlpp::tag::can_be_null>;
+      using value_type = ::sqlpp::compat::optional<::sqlpp::day_point>;
+      using _traits = ::sqlpp::make_traits<::sqlpp::day_point, ::sqlpp::tag::can_be_null, ::sqlpp::tag::has_default>;
     };
     struct TimePointN
     {
       struct _alias_t
       {
         static constexpr const char _literal[] =  "time_point_n";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -305,14 +276,15 @@ namespace test
             const T& operator()() const { return timePointN; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::time_point, sqlpp::tag::can_be_null>;
+      using value_type = ::sqlpp::compat::optional<::sqlpp::time_point>;
+      using _traits = ::sqlpp::make_traits<::sqlpp::time_point, ::sqlpp::tag::can_be_null, ::sqlpp::tag::has_default>;
     };
     struct TimeOfDayN
     {
       struct _alias_t
       {
         static constexpr const char _literal[] =  "time_of_day_n";
-        using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+        using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
         template<typename T>
         struct _member_t
           {
@@ -321,11 +293,12 @@ namespace test
             const T& operator()() const { return timeOfDayN; }
           };
       };
-      using _traits = sqlpp::make_traits<sqlpp::time_of_day, sqlpp::tag::can_be_null>;
+      using value_type = ::sqlpp::compat::optional<::sqlpp::time_of_day>;
+      using _traits = ::sqlpp::make_traits<::sqlpp::time_of_day, ::sqlpp::tag::can_be_null, ::sqlpp::tag::has_default>;
     };
   } // namespace TabDateTime_
 
-  struct TabDateTime: sqlpp::table_t<TabDateTime,
+  struct TabDateTime: ::sqlpp::table_t<TabDateTime,
                TabDateTime_::Id,
                TabDateTime_::DayPointN,
                TabDateTime_::TimePointN,
@@ -334,7 +307,7 @@ namespace test
     struct _alias_t
     {
       static constexpr const char _literal[] =  "tab_date_time";
-      using _name_t = sqlpp::make_char_sequence<sizeof(_literal), _literal>;
+      using _name_t = ::sqlpp::make_char_sequence<sizeof(_literal), _literal>;
       template<typename T>
       struct _member_t
       {