diff --git a/include/cpphibernate/context.h b/include/cpphibernate/context.h
index 02f10e7..2df4d92 100644
--- a/include/cpphibernate/context.h
+++ b/include/cpphibernate/context.h
@@ -53,13 +53,14 @@ beg_namespace_cpphibernate
             template<typename T_dataset, typename... T_modifiers>
             constexpr auto read(T_dataset& dataset, T_modifiers&&... modifiers)
                 -> mp::enable_if<
-                    modifier::all_are_modifier<mp::decay_t<T_modifiers>...>>
+                    modifier::all_are_modifiers<mp::decay_t<T_modifiers>...>>
             {
+                using namespace modifier;
                 using real_dataset_type = misc::real_dataset_t<mp::decay_t<T_dataset>>;
                 schema::tables::find(_schema.tables, hana::type_c<real_dataset_type>);
-                this->read_impl(dataset, hana::make_tuple(std::forward<T_modifiers>(modifiers)...));
+                this->read_impl(dataset, modifier::make_list(std::forward<T_modifiers>(modifiers)...));
             }
-            
+
             template<typename T_dataset>
             constexpr auto read(T_dataset& dataset)
                 -> mp::enable_if_c<
@@ -70,7 +71,7 @@ beg_namespace_cpphibernate
                 using real_dataset_type = misc::real_dataset_t<mp::decay_t<T_dataset>>;
                 auto& table         = schema::tables::find(_schema.tables, hana::type_c<real_dataset_type>);
                 auto& primary_key   = schema::table::get_primary_key_field(table);
-                this->read_impl(dataset, hana::make_tuple(where(equal(primary_key, primary_key.getter(dataset)))));
+                this->read_impl(dataset, modifier::make_list(where(equal(primary_key, primary_key.getter(dataset)))));
             }
 
             template<typename T_dataset>
@@ -82,7 +83,7 @@ beg_namespace_cpphibernate
                 using namespace modifier;
                 using real_dataset_type = misc::real_dataset_t<mp::decay_t<T_dataset>>;
                 schema::tables::find(_schema.tables, hana::type_c<real_dataset_type>);
-                this->read_impl(dataset, hana::make_tuple());
+                this->read_impl(dataset, modifier::make_list());
             }
 
             /* update */
diff --git a/include/cpphibernate/driver/mariadb/helper/context.h b/include/cpphibernate/driver/mariadb/helper/context.h
index e9859a1..561bea6 100644
--- a/include/cpphibernate/driver/mariadb/helper/context.h
+++ b/include/cpphibernate/driver/mariadb/helper/context.h
@@ -124,6 +124,7 @@ beg_namespace_cpphibernate_driver_mariadb
         const table_t*  derived_table;
         const field_t*  owner_field;
         std::string     owner_key;
+        ssize_t         index;
 
         template<typename T_data>
         inline create_update_context(
@@ -136,6 +137,7 @@ beg_namespace_cpphibernate_driver_mariadb
             , is_update     (p_is_update)
             , derived_table (nullptr)
             , owner_field   (nullptr)
+            , index         (-1)
             { }
     };
 
diff --git a/include/cpphibernate/driver/mariadb/helper/type_properties.h b/include/cpphibernate/driver/mariadb/helper/type_properties.h
index c7df09d..45ff6b6 100644
--- a/include/cpphibernate/driver/mariadb/helper/type_properties.h
+++ b/include/cpphibernate/driver/mariadb/helper/type_properties.h
@@ -211,7 +211,7 @@ beg_namespace_cpphibernate_driver_mariadb
     };
 
     template<typename T>
-    struct type_properties<T, mp::enable_if<misc::is_nullable<mp::clean_type<T>>>>
+    struct type_properties<T, mp::enable_if<misc::is_nullable<mp::decay_t<T>>>>
     {
         using nullable_type         = T;
         using nullable_helper_type  = misc::nullable_helper<nullable_type>;
diff --git a/include/cpphibernate/driver/mariadb/impl.h b/include/cpphibernate/driver/mariadb/impl.h
index a82fa8f..b990d17 100644
--- a/include/cpphibernate/driver/mariadb/impl.h
+++ b/include/cpphibernate/driver/mariadb/impl.h
@@ -1,3 +1,5 @@
 #pragma once
 
-#include <cpphibernate/driver/mariadb/impl/create_update.h>
\ No newline at end of file
+#include <cpphibernate/driver/mariadb/impl/create_update.h>
+#include <cpphibernate/driver/mariadb/impl/limit.h>
+#include <cpphibernate/driver/mariadb/impl/where.h>
\ No newline at end of file
diff --git a/include/cpphibernate/driver/mariadb/impl/create_update.h b/include/cpphibernate/driver/mariadb/impl/create_update.h
index e2d7f48..a51e6fe 100644
--- a/include/cpphibernate/driver/mariadb/impl/create_update.h
+++ b/include/cpphibernate/driver/mariadb/impl/create_update.h
@@ -99,11 +99,14 @@ beg_namespace_cpphibernate_driver_mariadb
             auto& dataset    = context.get<dataset_type>();
 
             transaction_lock trans(connection);
+            ssize_t index = 0;
             for (auto& x : dataset)
             {
                 using new_dataset_type            = mp::decay_t<decltype(x)>;
                 using new_create_update_impl_type = create_update_impl_t<new_dataset_type>;
-                new_create_update_impl_type::apply(change_context(context, x), strict);
+                auto new_context = change_context(context, x);
+                new_context.index = index++;
+                new_create_update_impl_type::apply(new_context, strict);
             }
             trans.commit();
             return ret;
diff --git a/include/cpphibernate/driver/mariadb/impl/limit.h b/include/cpphibernate/driver/mariadb/impl/limit.h
new file mode 100644
index 0000000..7e502c6
--- /dev/null
+++ b/include/cpphibernate/driver/mariadb/impl/limit.h
@@ -0,0 +1,65 @@
+#pragma once
+
+#include <cpphibernate/config.h>
+#include <cpphibernate/modifier.h>
+#include <cpphibernate/driver/mariadb/impl/modifier_tags.h>
+
+beg_namespace_cpphibernate_driver_mariadb
+{
+
+    /* limit_builder */
+
+    template<typename T_modifiers>
+    struct limit_builder
+    {
+        ::cppmariadb::statement statement;
+
+        limit_builder(const T_modifiers& modifier)
+        {
+            ssize_t limit = -1;
+            ssize_t offset = -1;
+
+            hana::for_each(modifier, [&limit, &offset](auto& modifier){
+                using modifier_type  = mp::decay_t<decltype(modifier)>;
+                using is_limit_type  = modifier::is_limit_modifier<modifier_type>;
+                using is_offset_type = modifier::is_offset_modifier<modifier_type>;
+                hana::eval_if(
+                    is_limit_type { },
+                    [&limit, &modifier](auto _){
+                        limit = hana::value(_(modifier).value);
+                    },
+                    [&offset, &modifier](){
+                        hana::eval_if(
+                            is_offset_type { },
+                            [&offset, &modifier](auto _){
+                                offset = hana::value(_(modifier).value);
+                            },
+                            []{
+                                /* no-op */
+                            });
+                    });
+            });
+
+            if (offset >= 0 && limit < 0)
+                limit = 1000000;
+
+            if (limit >= 0)
+            {
+                std::ostringstream ss;
+                ss << "LIMIT " << limit;
+                if (offset >= 0)
+                    ss << " OFFSET" << offset;
+                statement.assign(ss.str());
+            }
+        }
+    };
+
+    template<typename T_modifiers>
+    inline ::cppmariadb::statement& build_limit(const T_modifiers& modifiers)
+    {
+        static limit_builder<T_modifiers> builder(modifiers);
+        return builder.statement;
+    }
+
+}
+end_namespace_cpphibernate_driver_mariadb
diff --git a/include/cpphibernate/driver/mariadb/impl/modifier_tags.h b/include/cpphibernate/driver/mariadb/impl/modifier_tags.h
new file mode 100644
index 0000000..f1c6a9b
--- /dev/null
+++ b/include/cpphibernate/driver/mariadb/impl/modifier_tags.h
@@ -0,0 +1,69 @@
+#pragma once
+
+#include <cpphibernate/config.h>
+#include <cpphibernate/modifier.h>
+
+beg_namespace_cpphibernate_driver_mariadb
+{
+
+    namespace __impl
+    {
+
+        /* make_modifier_tags_impl */
+
+        template<typename X, typename = void>
+        struct make_modifier_tag_impl
+        {
+            template <typename ...T_args>
+            static constexpr decltype(auto) apply(T_args&&... args)
+                { static_assert(sizeof...(args) == -1, "Invalid parameters for make_modifier_tag(...)!"); }
+        };
+
+        template<typename T_modifier>
+        struct make_modifier_tag_impl<
+            mp::list<T_modifier>,
+            mp::enable_if_c<
+                    modifier::is_limit_modifier<mp::decay_t<T_modifier>>::value
+                ||  modifier::is_offset_modifier<mp::decay_t<T_modifier>>::value>>
+        {
+            static constexpr decltype(auto) apply(T_modifier&&)
+                { return T_modifier { }; }
+        };
+
+    }
+
+    constexpr decltype(auto) make_modifier_tag = misc::make_generic_predicate<__impl::make_modifier_tag_impl> { };
+
+    namespace __impl
+    {
+
+        /* make_modifier_tags_impl */
+
+        template<typename X, typename = void>
+        struct make_modifier_tags_impl
+        {
+            template <typename ...T_args>
+            static constexpr decltype(auto) apply(T_args&&... args)
+                { static_assert(sizeof...(args) == -1, "Invalid parameters for make_modifier_tags(...)!"); }
+        };
+
+        template<typename T_modifiers>
+        struct make_modifier_tags_impl<
+            mp::list<T_modifiers>,
+            mp::enable_if_c<
+                modifier::is_modifiers<mp::decay_t<T_modifiers>>::value>>
+        {
+            static constexpr decltype(auto) apply(T_modifiers&& modifiers)
+            {
+                return hana::transform(
+                    modifiers,
+                    make_modifier_tag);
+            }
+        };
+
+    }
+
+    constexpr decltype(auto) make_modifier_tags = misc::make_generic_predicate<__impl::make_modifier_tags_impl> { };
+
+}
+end_namespace_cpphibernate_driver_mariadb
diff --git a/include/cpphibernate/driver/mariadb/impl/where.h b/include/cpphibernate/driver/mariadb/impl/where.h
new file mode 100644
index 0000000..324a4b5
--- /dev/null
+++ b/include/cpphibernate/driver/mariadb/impl/where.h
@@ -0,0 +1,183 @@
+#pragma once
+
+#include <sstream>
+#include <cpphibernate/config.h>
+#include <cpphibernate/modifier.h>
+#include <cpphibernate/driver/mariadb/schema/schema.h>
+
+beg_namespace_cpphibernate_driver_mariadb
+{
+
+    /* where_builder */
+
+    template<typename T_modifiers>
+    struct where_builder
+    {
+    private:
+        struct build_t
+        {
+            const schema_t&     schema;
+            const T_modifiers&  modifiers;
+            std::ostringstream  os;
+
+            inline build_t(const schema_t& p_schema, const T_modifiers& p_modifiers)
+                : schema    (p_schema)
+                , modifiers (p_modifiers)
+                { }
+
+            template<typename T_clause>
+            inline auto build_clause(T_clause&& clause)
+                -> mp::enable_if<modifier::is_where_clause_and<mp::decay_t<T_clause>>>
+            {
+                os << "(";
+                build_clause(os, clause.clauses[hana::size_c<0>]);
+                os << ")";
+                hana::for_each(
+                    hana::remove_at(clause.clauses, hana::size_c<0>),
+                    [&](auto& clause) {
+                        os << " AND (";
+                        build_clause(os, clause);
+                        os << ")";
+                    });
+            }
+
+            template<typename T_clause>
+            inline auto build_clause(T_clause&& clause)
+                -> mp::enable_if<modifier::is_where_clause_or<mp::decay_t<T_clause>>>
+            {
+                os << "(";
+                build_clause(os, clause.clauses[hana::size_c<0>]);
+                os << ")";
+                hana::for_each(
+                    hana::remove_at(clause.clauses, hana::size_c<0>),
+                    [&](auto& clause) {
+                        os << " OR (";
+                        build_clause(os, clause);
+                        os << ")";
+                    });
+            }
+
+            template<typename T_clause>
+            inline auto build_clause(T_clause&& clause)
+                -> mp::enable_if<modifier::is_where_clause_not<mp::decay_t<T_clause>>>
+            {
+                os << "NOT (";
+                build_clause(os, clause.clause);
+                os << ")";
+            }
+
+            template<typename T_clause>
+            inline auto build_clause(T_clause&& clause)
+                -> mp::enable_if<modifier::is_where_clause_equal<mp::decay_t<T_clause>>>
+            {
+                auto field_id = misc::get_type_id(hana::type_c<mp::decay_t<decltype(clause.field)>>);
+                auto& field = schema.field(field_id);
+                os  <<  "`"
+                    <<  field.table_name
+                    <<  "`.`"
+                    <<  field.field_name
+                    <<  "`="
+                    <<  field.convert_to_open
+                    <<  "?\?"
+                    <<  field.convert_to_close;
+            }
+
+            inline void build(::cppmariadb::statement& statement)
+            {
+                size_t index = 0;
+                hana::for_each(modifiers, [&](auto& modifier){
+                    using modifier_type = mp::decay_t<decltype(modifier)>;
+                    using is_where_type = modifier::is_where_modifier<modifier_type>;
+                    hana::eval_if(
+                        is_where_type { },
+                        [&](auto _){
+                            if (index++ == 0)   os << "WHERE (";
+                            else                os << " AND (";
+                            build_clause(_(modifier).clause);
+                            os << ")";
+                        },
+                        []{ });
+                });
+                os << ")";
+                statement.assign(os.str());
+            }
+        };
+
+        struct assign_t
+        {
+            ::cppmariadb::statement&    statement;
+            const T_modifiers&          modifiers;
+            size_t                      index { 0 };
+
+            inline assign_t(::cppmariadb::statement& p_statement, const T_modifiers& p_modifiers)
+                : statement(p_statement)
+                , modifiers(p_modifiers)
+                { }
+
+            template<typename T_clause>
+            inline auto assign_clause(T_clause&& clause)
+                -> mp::enable_if_c<
+                        modifier::is_where_clause_and<mp::decay_t<T_clause>>::value
+                    ||  modifier::is_where_clause_or <mp::decay_t<T_clause>>::value>
+            {
+                hana::for_each([&](auto& clause) {
+                    assign_clause(clause);
+                });
+            }
+
+            template<typename T_clause>
+            inline auto assign_clause(T_clause&& clause)
+                -> mp::enable_if<modifier::is_where_clause_not<mp::decay_t<T_clause>>>
+            {
+                assign_clause(clause.clause);
+            }
+
+            template<typename T_clause>
+            inline auto assign_clause(T_clause&& clause)
+                -> mp::enable_if<modifier::is_where_clause_equal<mp::decay_t<T_clause>>>
+            {
+                statement.set(index, clause.value);
+                ++index;
+            }
+
+            inline void assign()
+            {
+                hana::for_each(modifiers, [&](auto& modifier){
+                    using modifier_type = mp::decay_t<decltype(modifier)>;
+                    using is_where_type = modifier::is_where_modifier<modifier_type>;
+                    hana::eval_if(
+                        is_where_type { },
+                        [&](auto _){
+                            assign_clause(_(modifier).clause);
+                        },
+                        []{ });
+                });
+            }
+        };
+
+    private:
+        const schema_t*         _schema     { nullptr };
+        ::cppmariadb::statement _statement;
+
+    public:
+        inline ::cppmariadb::statement& assign(const schema_t& schema, const T_modifiers& modifiers)
+        {
+            if (_schema != &schema)
+            {
+                build_t(schema, modifiers).build(_statement);
+                _schema = &schema;
+            }
+            assign_t(_statement, modifiers).assign();
+            return _statement;
+        }
+    };
+
+    template<typename T_modifiers>
+    inline decltype(auto) build_where(const schema_t& schema, const T_modifiers& modifiers)
+    {
+        static where_builder<T_modifiers> builder;
+        return builder.assign(schema, modifiers);
+    }
+
+}
+end_namespace_cpphibernate_driver_mariadb
diff --git a/include/cpphibernate/driver/mariadb/mariadb.h b/include/cpphibernate/driver/mariadb/mariadb.h
index 49243d4..2e7fe06 100644
--- a/include/cpphibernate/driver/mariadb/mariadb.h
+++ b/include/cpphibernate/driver/mariadb/mariadb.h
@@ -40,6 +40,15 @@ beg_namespace_cpphibernate_driver_mariadb
             create_update_impl_t<T_dataset>::apply(
                 create_update_context(dataset, _schema, _connection, _filter, false));
         }
+
+        template<typename T_dataset, typename T_modifiers>
+        inline void read_impl(T_dataset& dataset, T_modifiers&& modifiers) const
+        {
+            auto& where = build_where(_schema, modifiers);
+            auto& limit = build_limit(modifiers);
+            std::cout << "WHERE = " << where.query(_connection) << std::endl;
+            std::cout << "LIMIT = " << limit.query(_connection) << std::endl;
+        }
     };
 
 }
diff --git a/include/cpphibernate/driver/mariadb/schema/field.h b/include/cpphibernate/driver/mariadb/schema/field.h
index e7947ee..87869b7 100644
--- a/include/cpphibernate/driver/mariadb/schema/field.h
+++ b/include/cpphibernate/driver/mariadb/schema/field.h
@@ -17,104 +17,128 @@ beg_namespace_cpphibernate_driver_mariadb
 
     struct field_t
     {
-        size_t          table_dataset_id    { 0 };
-        size_t          value_dataset_id    { 0 };
-        bool            value_is_nullable   { false };
-        bool            value_is_container  { false };
-        std::string     schema_name;
-        std::string     table_name;
-        std::string     field_name;
-        attributes_t    attributes;
-
-        const table_t*  table               { nullptr };
-        const table_t*  referenced_table    { nullptr };
+        size_t          id                          { 0 };          // unique id of the field
+        size_t          dataset_id                  { 0 };          // unique id of the dataset type
+        size_t          real_dataset_id             { 0 };          // unique id of the real/unwrapped dataset type
+        size_t          value_id                    { 0 };          // unique id of the value type
+        size_t          real_value_id               { 0 };          // unique id of the real/unwrapped value type
+
+        bool            value_is_nullable           { false };      // value is stored in a nullable container
+        bool            value_is_container          { false };      // value is stored in a container
+        bool            value_is_ordered            { false };      // value is stored in a ordered container (vector, list, ...)
+        bool            value_is_auto_incremented   { false };      // value is a auto incremented field
+
+        const table_t*  table                       { nullptr };    // table this field belongs to
+        const table_t*  referenced_table            { nullptr };    // table that belongs to the value (if exists)
+
+        std::string     schema_name;                                // name of the SQL schema
+        std::string     table_name;                                 // name of the SQL table
+        std::string     field_name;                                 // name of the SQL field
+        std::string     type;                                       // SQL type name
+        std::string     create_arguments;                           // additional arguments for CREATE TABLE command
+
+        std::string     convert_to_open;                            // SQL code to open the "convert to" operation
+        std::string     convert_to_close;                           // SQL code to close the "convert to" operation
+        std::string     convert_from_open;                          // SQL code to open the "convert from" operation
+        std::string     convert_from_close;                         // SQL code to close the "convert from" operation
+
+        attributes_t    attributes;                                 // attributes for the field
 
         inline field_t() = default;
         inline field_t(const field_t&) = delete;
         inline field_t(field_t&& other)
-            : table_dataset_id  (std::move(other).table_dataset_id)
-            , value_dataset_id  (std::move(other).value_dataset_id)
-            , value_is_nullable (std::move(other).value_is_nullable)
-            , value_is_container(std::move(other).value_is_container)
-            , schema_name       (std::move(other).schema_name)
-            , table_name        (std::move(other).table_name)
-            , field_name        (std::move(other).field_name)
-            , attributes        (std::move(other).attributes)
-            , table             (nullptr)
-            , referenced_table  (nullptr)
+            : id                        (std::move(other).id)
+            , dataset_id                (std::move(other).dataset_id)
+            , real_dataset_id           (std::move(other).real_dataset_id)
+            , value_id                  (std::move(other).value_id)
+            , real_value_id             (std::move(other).real_value_id)
+            , value_is_nullable         (std::move(other).value_is_nullable)
+            , value_is_container        (std::move(other).value_is_container)
+            , value_is_auto_incremented (std::move(other).value_is_auto_incremented)
+            , table                     (nullptr)
+            , referenced_table          (nullptr)
+            , schema_name               (std::move(other).schema_name)
+            , table_name                (std::move(other).table_name)
+            , field_name                (std::move(other).field_name)
+            , type                      (std::move(other).type)
+            , create_arguments          (std::move(other).create_arguments)
+            , convert_to_open           (std::move(other).convert_to_open)
+            , convert_to_close          (std::move(other).convert_to_close)
+            , convert_from_open         (std::move(other).convert_from_open)
+            , convert_from_close        (std::move(other).convert_from_close)
+            , attributes                (std::move(other).attributes)
             { }
         virtual ~field_t() { };
 
-        void print(std::ostream& os) const;
+                void        print                   (std::ostream& os) const;
+        virtual void        update                  ();
 
         /* CRUD */
-        virtual value_t foreign_create_update(const create_update_context& context) const;
+        virtual value_t     foreign_create_update   (const create_update_context& context) const;
 
         /* properties */
-        virtual std::string type                    () const;
-        virtual std::string create_table_arguments  () const;
-        virtual std::string generate_value          (::cppmariadb::connection& connection) const;
-        virtual bool        is_auto_generated       () const;
-        virtual bool        is_default              (const data_context& context) const;
-        virtual std::string convert_to_open         () const;
-        virtual std::string convert_to_close        () const;
-        virtual std::string convert_from_open       () const;
-        virtual std::string convert_from_close      () const;
         virtual value_t     get                     (const data_context& context) const;
         virtual void        set                     (const data_context& context, const value_t&) const;
+        virtual bool        is_default              (const data_context& context) const;
+        virtual std::string generate_value          (::cppmariadb::connection& connection) const;
     };
 
     /* simple_field_t */
 
-    template<typename T_schema, typename T_field>
+    template<typename T_field>
     struct simple_field_t
         : public field_t
     {
-        using schema_type   = T_schema;
-        using field_type    = T_field;
-        using getter_type   = typename mp::decay_t<field_type>::getter_type;
-        using dataset_type  = typename getter_type::dataset_type;
-        using value_type    = typename getter_type::value_type;
-
-        const schema_type&  schema;
-        const field_type&   field;
-
-        inline simple_field_t(const schema_type& p_schema, const field_type& p_field)
+        using base_type         = field_t;
+        using field_type        = T_field;
+        using getter_type       = typename mp::decay_t<field_type>::getter_type;
+        using dataset_type      = typename getter_type::dataset_type;
+        using real_dataset_type = misc::real_dataset_t<dataset_type>;
+        using value_type        = typename getter_type::value_type;
+        using real_value_type   = misc::real_dataset_t<value_type>;
+        using type_props        = type_properties<value_type>;
+
+        const field_type& field;
+
+        inline simple_field_t(const field_type& p_field)
             : field_t   ()
-            , schema    (p_schema)
             , field     (p_field)
             { }
+
+        virtual void update() override;
     };
 
     /* value_field_t */
 
-    template<typename T_schema, typename T_field>
+    template<typename T_field>
     struct value_field_t
-        : public simple_field_t<T_schema, T_field>
+        : public simple_field_t<T_field>
     {
-        using base_type     = simple_field_t<T_schema, T_field>;
-        using schema_type   = T_schema;
-        using field_type    = T_field;
-        using getter_type   = typename base_type::getter_type;
-        using dataset_type  = typename base_type::dataset_type;
-        using value_type    = typename base_type::value_type;
-        using type_props    = type_properties<value_type>;
+        using base_type         = simple_field_t<T_field>;
+        using field_type        = typename base_type::field_type;
+        using getter_type       = typename base_type::getter_type;
+        using dataset_type      = typename base_type::dataset_type;
+        using real_dataset_type = typename base_type::dataset_type;
+        using value_type        = typename base_type::value_type;
+        using real_value_type   = typename base_type::real_value_type;
+        using type_props        = typename base_type::type_props;
 
         using base_type::base_type;
 
-        virtual std::string type() const override;
-        virtual value_t     get (const data_context& context) const override;
-        virtual void        set (const data_context& context, const value_t&) const override;
+        static_assert(mp::is_same<dataset_type, real_dataset_type>::value, "internal error: dataset type mismatch!");
+
+        virtual void    update  () override;
+        virtual value_t get     (const data_context& context) const override;
+        virtual void    set     (const data_context& context, const value_t&) const override;
     };
 
     /* primary_key_field_t */
 
-    template<typename T_schema, typename T_field>
+    template<typename T_field>
     struct primary_key_field_t
-        : public value_field_t<T_schema, T_field>
+        : public value_field_t<T_field>
     {
-        using base_type     = value_field_t<T_schema, T_field>;
-        using schema_type   = typename base_type::schema_type;
+        using base_type     = value_field_t<T_field>;
         using field_type    = typename base_type::field_type;
         using dataset_type  = typename base_type::dataset_type;
         using value_type    = typename base_type::value_type;
@@ -122,35 +146,29 @@ beg_namespace_cpphibernate_driver_mariadb
 
         using base_type::base_type;
 
-        virtual std::string create_table_arguments  () const override;
-        virtual std::string generate_value          (::cppmariadb::connection& connection) const override;
-        virtual bool        is_auto_generated       () const override;
-        virtual bool        is_default              (const data_context& context) const override;
-        virtual std::string convert_to_open         () const override;
-        virtual std::string convert_to_close        () const override;
-        virtual std::string convert_from_open       () const override;
-        virtual std::string convert_from_close      () const override;
+        virtual bool        is_default    (const data_context& context) const override;
+        virtual std::string generate_value(::cppmariadb::connection& connection) const override;
     };
 
     /* data_field_t */
 
-    template<typename T_schema, typename T_field>
+    template<typename T_field>
     struct data_field_t
-        : public value_field_t<T_schema, T_field>
+        : public value_field_t<T_field>
     {
-        using base_type = value_field_t<T_schema, T_field>;
+        using base_type = value_field_t<T_field>;
 
         using base_type::base_type;
     };
 
     /* foreign_table_field_t */
 
-    template<typename T_schema, typename T_field>
+    template<typename T_field>
     struct foreign_table_field_t
-        : public simple_field_t<T_schema, T_field>
+        : public simple_field_t<T_field>
     {
     public:
-        using base_type     = simple_field_t<T_schema, T_field>;
+        using base_type     = simple_field_t<T_field>;
         using dataset_type  = typename base_type::dataset_type;
 
         using base_type::base_type;
diff --git a/include/cpphibernate/driver/mariadb/schema/field.inl b/include/cpphibernate/driver/mariadb/schema/field.inl
index 2820537..1901a72 100644
--- a/include/cpphibernate/driver/mariadb/schema/field.inl
+++ b/include/cpphibernate/driver/mariadb/schema/field.inl
@@ -6,21 +6,46 @@
 beg_namespace_cpphibernate_driver_mariadb
 {
 
+    /* simple_field_t */
+
+    template<typename T_field>
+    void simple_field_t<T_field>
+        ::update()
+    {
+        base_type::update();
+
+        id              = misc::get_type_id(hana::type_c<field_type>);
+        dataset_id      = misc::get_type_id(hana::type_c<dataset_type>);
+        real_dataset_id = misc::get_type_id(hana::type_c<real_dataset_type>);
+        value_id        = misc::get_type_id(hana::type_c<value_type>);
+        real_value_id   = misc::get_type_id(hana::type_c<real_value_type>);
+
+        value_is_nullable  = misc::is_nullable<value_type>::value;
+        value_is_container = misc::is_container<value_type>::value;
+        value_is_ordered   = misc::is_ordered<value_type>::value;
+    }
+
     /* value_field_t */
 
-    template<typename T_schema, typename T_field>
-    std::string value_field_t<T_schema, T_field>::type() const
-        { return type_props::type(); }
+    template<typename T_field>
+    void value_field_t<T_field>
+        ::update()
+    {
+        base_type::update();
+        this->type = type_props::type();
+    }
 
-    template<typename T_schema, typename T_field>
-    value_t value_field_t<T_schema, T_field>::get(const data_context& context) const
+    template<typename T_field>
+    value_t value_field_t<T_field>
+        ::get(const data_context& context) const
     {
         auto& dataset = context.get<dataset_type>();
         return type_props::convert_from(this->field.getter(dataset));
     }
 
-    template<typename T_schema, typename T_field>
-    void value_field_t<T_schema, T_field>::set(const data_context& context, const value_t& value) const
+    template<typename T_field>
+    void value_field_t<T_field>
+        ::set(const data_context& context, const value_t& value) const
     {
         auto& dataset = context.get<dataset_type>();
         this->field.setter(dataset, type_props::convert_to(value));
@@ -28,12 +53,16 @@ beg_namespace_cpphibernate_driver_mariadb
 
     /* primary_key_field_t */
 
-    template<typename T_schema, typename T_field>
-    std::string primary_key_field_t<T_schema, T_field>::create_table_arguments() const
-        { return key_props::create_table_argument; }
+    template<typename T_field>
+    bool primary_key_field_t<T_field>
+        ::is_default(const data_context& context) const
+    {
+        auto& dataset = context.get<dataset_type>();
+        return key_props::is_default(this->field.getter(dataset));
+    }
 
-    template<typename T_schema, typename T_field>
-    std::string primary_key_field_t<T_schema, T_field>
+    template<typename T_field>
+    std::string primary_key_field_t<T_field>
         ::generate_value(::cppmariadb::connection& connection) const
     {
         auto ret = connection.execute_used(key_props::create_key_query);
@@ -42,37 +71,10 @@ beg_namespace_cpphibernate_driver_mariadb
         return ret->current()->at(0).template get<std::string>();
     }
 
-    template<typename T_schema, typename T_field>
-    bool primary_key_field_t<T_schema, T_field>::is_auto_generated() const
-        { return key_props::auto_generated::value; }
-
-    template<typename T_schema, typename T_field>
-    bool primary_key_field_t<T_schema, T_field>::is_default(const data_context& context) const
-    {
-        auto& dataset = context.get<dataset_type>();
-        return key_props::is_default(this->field.getter(dataset));
-    }
-
-    template<typename T_schema, typename T_field>
-    std::string primary_key_field_t<T_schema, T_field>::convert_to_open() const
-        { return key_props::convert_to_open; }
-
-    template<typename T_schema, typename T_field>
-    std::string primary_key_field_t<T_schema, T_field>::convert_to_close() const
-        { return key_props::convert_to_close; }
-
-    template<typename T_schema, typename T_field>
-    std::string primary_key_field_t<T_schema, T_field>::convert_from_open() const
-        { return key_props::convert_from_open; }
-
-    template<typename T_schema, typename T_field>
-    std::string primary_key_field_t<T_schema, T_field>::convert_from_close() const
-        { return key_props::convert_from_close; }
-
     /* foreign_table_field_t */
 
-    template<typename T_schema, typename T_field>
-    value_t foreign_table_field_t<T_schema, T_field>
+    template<typename T_field>
+    value_t foreign_table_field_t<T_field>
         ::foreign_create_update(const create_update_context& context) const
     {
         auto& dataset       = context.get<dataset_type>();
@@ -114,15 +116,15 @@ beg_namespace_cpphibernate_driver_mariadb
 
         template<typename T_schema, typename T_field, typename = void>
         struct field_type
-            { using type = data_field_t<T_schema, T_field>; };
+            { using type = data_field_t<T_field>; };
 
         template<typename T_schema, typename T_field>
         struct field_type<T_schema, T_field, mp::enable_if<is_primary_key_field<T_field>>>
-            { using type = primary_key_field_t<T_schema, T_field>; };
+            { using type = primary_key_field_t<T_field>; };
 
         template<typename T_schema, typename T_field>
         struct field_type<T_schema, T_field, mp::enable_if<is_foreign_table_field<T_schema, T_field>>>
-            { using type = foreign_table_field_t<T_schema, T_field>; };
+            { using type = foreign_table_field_t<T_field>; };
 
         template<typename T_schema, typename T_field>
         using field_type_t = typename field_type<T_schema, T_field>::type;
@@ -149,17 +151,9 @@ beg_namespace_cpphibernate_driver_mariadb
             {
                 using schema_type           = mp::decay_t<T_schema>;
                 using field_type            = mp::decay_t<T_field>;
-                using getter_type           = mp::decay_t<typename field_type::getter_type>;
-                using value_type            = mp::decay_t<typename getter_type::value_type>;
-                using dataset_type          = mp::decay_t<typename getter_type::dataset_type>;
-                using value_dataset_type    = misc::real_dataset_t<value_type>;
                 using return_type           = field_type_t<schema_type, field_type>;
-                using primary_key_type      = primary_key_field_t<schema_type, field_type>;
-                return_type ret(schema, field);
-                ret.table_dataset_id   = misc::get_type_id(hana::type_c<dataset_type>);
-                ret.value_dataset_id   = misc::get_type_id(hana::type_c<value_dataset_type>);
-                ret.value_is_nullable  = misc::is_nullable<value_type>::value;
-                ret.value_is_container = misc::is_container<value_type>::value;
+                using primary_key_type      = primary_key_field_t<field_type>;
+                return_type ret(field);
                 ret.schema_name        = schema.name;
                 ret.table_name         = table.name;
                 ret.field_name         = field.name;
diff --git a/include/cpphibernate/driver/mariadb/schema/schema.h b/include/cpphibernate/driver/mariadb/schema/schema.h
index ad8abd1..2b3498b 100644
--- a/include/cpphibernate/driver/mariadb/schema/schema.h
+++ b/include/cpphibernate/driver/mariadb/schema/schema.h
@@ -27,6 +27,7 @@ beg_namespace_cpphibernate_driver_mariadb
         void print  (std::ostream& os) const;
 
         const table_t& table(size_t dataset_id) const;
+        const field_t& field(size_t field_id) const;
 
         /* CRUD */
         void init(const init_context& context) const;
diff --git a/include/cpphibernate/driver/mariadb/schema/table.inl b/include/cpphibernate/driver/mariadb/schema/table.inl
index bfb4b4b..812bb64 100644
--- a/include/cpphibernate/driver/mariadb/schema/table.inl
+++ b/include/cpphibernate/driver/mariadb/schema/table.inl
@@ -150,8 +150,11 @@ beg_namespace_cpphibernate_driver_mariadb
                                                             std::declval<T_table>().wrapped_dataset))>;
                 using wrapped_dataset_type          = typename mp::decay_t<T_table>::wrapped_dataset_type;
                 using dataset_type                  = misc::unwrap_t<wrapped_dataset_type>;
+                using real_dataset_type             = misc::real_dataset_t<dataset_type>;
                 using table_type                    = table_type_t<dataset_type, base_type>;
 
+                static_assert(mp::is_same<dataset_type, real_dataset_type>::value, "table cn only be created for simple dataset types (not for containers)!");
+
                 table_type ret(schema, table);
                 ret.dataset_id          = misc::get_type_id(table.wrapped_dataset);
                 ret.base_dataset_id     = misc::get_type_id(wrapped_base_type { });
diff --git a/include/cpphibernate/misc/container_helper.h b/include/cpphibernate/misc/container_helper.h
new file mode 100644
index 0000000..7f64153
--- /dev/null
+++ b/include/cpphibernate/misc/container_helper.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include <set>
+#include <list>
+#include <vector>
+
+#include <cpphibernate/config.h>
+
+beg_namespace_cpphibernate_misc
+{
+
+    /* container_helper */
+
+    template<typename T_container, typename = void>
+    struct container_helper
+    {
+        using container_type = T_container;
+        using value_type     = real_dataset_t<container_type>;
+    };
+
+}
+end_namespace_cpphibernate_misc
\ No newline at end of file
diff --git a/include/cpphibernate/misc/meta.h b/include/cpphibernate/misc/meta.h
index 2821f37..df78aff 100644
--- a/include/cpphibernate/misc/meta.h
+++ b/include/cpphibernate/misc/meta.h
@@ -22,13 +22,13 @@ beg_namespace_cpphibernate_misc
             : public mp::c_false_t
             { };
 
-        template<typename T>
-        struct is_container_impl<std::list<T>>
+        template<typename T, typename... T_args>
+        struct is_container_impl<std::list<T, T_args...>>
             : public mp::c_true_t
             { };
 
-        template<typename T>
-        struct is_container_impl<std::vector<T>>
+        template<typename T, typename... T_args>
+        struct is_container_impl<std::vector<T, T_args...>>
             : public mp::c_true_t
             { };
 
@@ -71,6 +71,23 @@ beg_namespace_cpphibernate_misc
             : public mp::c_true_t
             { };
 
+        /* is_ordered_impl */
+
+        template<typename T>
+        struct is_ordered_impl
+            : public mp::c_false_t
+            { };
+
+        template<typename T, typename... T_args>
+        struct is_ordered_impl<std::list<T, T_args...>>
+            : public mp::c_true_t
+            { };
+
+        template<typename T, typename... T_args>
+        struct is_ordered_impl<std::vector<T, T_args...>>
+            : public mp::c_true_t
+            { };
+
         /* real_dataset_impl */
 
         template<typename T, typename = void>
@@ -81,22 +98,21 @@ beg_namespace_cpphibernate_misc
         struct real_dataset_impl<utl::nullable<T>, void>
             { using type = typename real_dataset_impl<T>::type; };
 
-        template<typename T>
-        struct real_dataset_impl<std::unique_ptr<T>, void>
+        template<typename T, typename... T_args>
+        struct real_dataset_impl<std::unique_ptr<T, T_args...>, void>
             { using type = typename real_dataset_impl<T>::type; };
 
         template<typename T>
         struct real_dataset_impl<std::shared_ptr<T>, void>
             { using type = typename real_dataset_impl<T>::type; };
 
-        template<typename T>
-        struct real_dataset_impl<std::vector<T>, void>
+        template<typename T, typename... T_args>
+        struct real_dataset_impl<std::list<T, T_args...>, void>
             { using type = typename real_dataset_impl<T>::type; };
 
-        template<typename T>
-        struct real_dataset_impl<std::list<T>, void>
+        template<typename T, typename... T_args>
+        struct real_dataset_impl<std::vector<T, T_args...>, void>
             { using type = typename real_dataset_impl<T>::type; };
-
     }
 
     /* meta */
@@ -111,6 +127,11 @@ beg_namespace_cpphibernate_misc
         : public __impl::is_nullable_impl<T>
         { };
 
+    template<typename T>
+    struct is_ordered
+        : public __impl::is_ordered_impl<T>
+        { };
+
     template<typename T>
     struct is_pointer
         : public __impl::is_pointer_impl<T>
diff --git a/include/cpphibernate/modifier.h b/include/cpphibernate/modifier.h
index 32b12a1..474cf89 100644
--- a/include/cpphibernate/modifier.h
+++ b/include/cpphibernate/modifier.h
@@ -2,5 +2,6 @@
 
 #include <cpphibernate/modifier/limit.h>
 #include <cpphibernate/modifier/modifier.h>
+#include <cpphibernate/modifier/modifiers.h>
 #include <cpphibernate/modifier/offset.h>
 #include <cpphibernate/modifier/where.h>
\ No newline at end of file
diff --git a/include/cpphibernate/modifier/modifier.h b/include/cpphibernate/modifier/modifier.h
index 766b202..5e24e90 100644
--- a/include/cpphibernate/modifier/modifier.h
+++ b/include/cpphibernate/modifier/modifier.h
@@ -23,7 +23,7 @@ beg_namespace_cpphibernate_modifier
         { };
 
     template<typename... T>
-    struct all_are_modifier
+    struct all_are_modifiers
         : public mp::all_true<is_modifier<T>::value...>
         { };
 
diff --git a/include/cpphibernate/modifier/modifiers.h b/include/cpphibernate/modifier/modifiers.h
new file mode 100644
index 0000000..f1b5782
--- /dev/null
+++ b/include/cpphibernate/modifier/modifiers.h
@@ -0,0 +1,65 @@
+#pragma once
+
+#include <cpphibernate/misc.h>
+#include <cpphibernate/config.h>
+#include <cpphibernate/modifier/modifier.h>
+
+beg_namespace_cpphibernate_modifier
+{
+
+    namespace __impl
+    {
+
+        /* is_modifiers_impl */
+
+        template<typename T, typename = void>
+        struct is_modifiers_impl
+            : mp::c_false_t
+            { };
+
+        template<typename... T>
+        struct is_modifiers_impl<hana::basic_tuple<T...>, mp::enable_if<all_are_modifiers<T...>>>
+            : mp::c_true_t
+            { };
+
+    }
+
+    /* meta */
+
+    template<typename T>
+    struct is_modifiers
+        : public __impl::is_modifiers_impl<T>
+        { };
+
+    /* operations */
+
+    namespace __impl
+    {
+
+        /* make_modifiers_impl */
+
+        template<typename T, typename = void>
+        struct make_modifiers_impl
+        {
+            template<typename... T_args>
+            static constexpr decltype(auto) apply(T_args&&...)
+                { static_assert(sizeof...(T_args) == -1, "Invalid parameters for hibernate::schema::modifier::make(...)!"); }
+        };
+
+        template<typename... T>
+        struct make_modifiers_impl<
+            mp::list<T...>,
+            mp::enable_if_c<
+                all_are_modifiers<mp::decay_t<T>...>::value>>
+        {
+            template<typename... T_args>
+            static constexpr decltype(auto) apply(T_args&&... args)
+                { return hana::make_basic_tuple(std::forward<T_args>(args)...); }
+        };
+
+    }
+
+    constexpr decltype(auto) make_list = misc::make_generic_predicate<__impl::make_modifiers_impl> { };
+
+}
+end_namespace_cpphibernate_modifier
\ No newline at end of file
diff --git a/include/cpphibernate/modifier/where/clauses.h b/include/cpphibernate/modifier/where/clauses.h
index db63fbb..f716bce 100644
--- a/include/cpphibernate/modifier/where/clauses.h
+++ b/include/cpphibernate/modifier/where/clauses.h
@@ -3,4 +3,5 @@
 #include <cpphibernate/modifier/where/clauses/and.h>
 #include <cpphibernate/modifier/where/clauses/clause.h>
 #include <cpphibernate/modifier/where/clauses/equal.h>
-#include <cpphibernate/modifier/where/clauses/not.h>
\ No newline at end of file
+#include <cpphibernate/modifier/where/clauses/not.h>
+#include <cpphibernate/modifier/where/clauses/or.h>
\ No newline at end of file
diff --git a/src/driver/mariadb/schema/field.cpp b/src/driver/mariadb/schema/field.cpp
index cea41c3..771cef2 100644
--- a/src/driver/mariadb/schema/field.cpp
+++ b/src/driver/mariadb/schema/field.cpp
@@ -17,111 +17,143 @@ void field_t::print(std::ostream& os) const
 {
     os  << indent << '{'
         << incindent
-            << indent << "\"table_dataset_id\": "   <<  table_dataset_id << ","
-            << indent << "\"value_dataset_id\": "   <<  value_dataset_id << ","
-            << indent << "\"value_is_nullable\": "  <<  (value_is_nullable ? "true" : "false") << ","
-            << indent << "\"value_is_container\": " <<  (value_is_container ? "true" : "false") << ","
-            << indent << "\"schema_name\": \""      <<  schema_name << "\","
-            << indent << "\"table_name\": \""       <<  table_name << "\","
-            << indent << "\"field_name\": \""       <<  field_name << "\","
-            << indent << "\"attributes\": "         <<  misc::print_container(attributes, false) << ","
-            << indent << "\"table\": "              << (table ? std::string("\"") + table->table_name + "\"" : "null") << ","
-            << indent << "\"referenced_table\": "   << (referenced_table ? std::string("\"") + referenced_table->table_name + "\"" : "null")
-        << decindent
-        << indent << '}';
-}
-
-#define throw_not_implemented(p_ret, p_name, ...)               \
-    p_ret field_t::p_name(__VA_ARGS__) const                    \
-    {                                                           \
-        throw misc::hibernate_exception(                        \
-            std::string("'") + table_name + "." + field_name +  \
-            "' does not implement the " #p_name "() method!");  \
-    }
 
-/* CRUD */
+            << indent << "\"id\": "                         <<  id << ","
+            << indent << "\"dataset_id\": "                 <<  dataset_id << ","
+            << indent << "\"real_dataset_id\": "            <<  real_dataset_id << ","
+            << indent << "\"value_id\": "                   <<  value_id << ","
+            << indent << "\"real_value_id\": "              <<  real_value_id << ","
+            << indent << "\"value_is_nullable\": "          <<  (value_is_nullable ? "true" : "false") << ","
+            << indent << "\"value_is_container\": "         <<  (value_is_container ? "true" : "false") << ","
+            << indent << "\"value_is_auto_incremented\": "  <<  (value_is_auto_incremented ? "true" : "false") << ","
+            << indent << "\"table\": "                      << (table ? std::string("\"") + table->table_name + "\"" : "null") << ","
+            << indent << "\"referenced_table\": "           << (referenced_table ? std::string("\"") + referenced_table->table_name + "\"" : "null") << ","
 
-throw_not_implemented(value_t,  foreign_create_update, const create_update_context&)
+            << indent << "\"schema_name\": \""              <<  schema_name << "\","
+            << indent << "\"table_name\": \""               <<  table_name << "\","
+            << indent << "\"field_name\": \""               <<  field_name << "\","
+            << indent << "\"type\": \""                     <<  type << "\","
+            << indent << "\"create_arguments\": \""         <<  create_arguments << "\","
 
-/* properties */
+            << indent << "\"convert_to_open\": \""          <<  convert_to_open << "\","
+            << indent << "\"convert_to_close\": \""         <<  convert_to_close << "\","
+            << indent << "\"convert_from_open\": \""        <<  convert_from_open << "\","
+            << indent << "\"convert_from_close\": \""       <<  convert_from_close << "\","
 
-throw_not_implemented(bool,     is_default, const data_context& context)
-throw_not_implemented(string,   type)
-throw_not_implemented(string,   create_table_arguments)
-throw_not_implemented(string,   generate_value, ::cppmariadb::connection&)
-throw_not_implemented(value_t,  get, const data_context& context)
-throw_not_implemented(void,     set, const data_context& context, const value_t&)
+            << indent << "\"attributes\": "                 <<  misc::print_container(attributes, false)
 
-bool field_t::is_auto_generated() const
-    { return false; }
+        << decindent
+        << indent << '}';
+}
 
-std::string field_t::convert_to_open() const
+void field_t::update()
 {
-    std::ostringstream ss;
-    for (auto it = this->attributes.begin(); it != this->attributes.end(); ++it)
+    id                          = 0;
+    dataset_id                  = 0;
+    real_dataset_id             = 0;
+    value_id                    = 0;
+    real_value_id               = 0;
+    value_is_nullable           = false;
+    value_is_container          = false;
+    value_is_auto_incremented   = false;
+    table                       = nullptr;
+    referenced_table            = nullptr;
+
+    type.clear();
+    create_arguments.clear();
+
+    /* conver_to_open */
     {
-        switch(*it)
+        std::ostringstream ss;
+        for (auto it = this->attributes.begin(); it != this->attributes.end(); ++it)
         {
-            case attribute_t::hex:         ss << "HEX(";       break;
-            case attribute_t::compress:    ss << "COMPRESS(";  break;
-            case attribute_t::primary_key:                     break;
+            switch(*it)
+            {
+                case attribute_t::hex:
+                    ss << "HEX(";
+                    break;
+                case attribute_t::compress:
+                    ss << "COMPRESS(";
+                    break;
+                case attribute_t::primary_key:
+                    ss << "UuidToBin(";
+                    break;
+            }
         }
+        convert_to_open = ss.str();
     }
-    return ss.str();
-}
 
-std::string field_t::convert_to_close() const
-{
-    std::ostringstream ss;
-    for (auto it = this->attributes.begin(); it != this->attributes.end(); ++it)
+    /* convert_to_close */
     {
-        switch(*it)
+        std::ostringstream ss;
+        for (auto it = this->attributes.begin(); it != this->attributes.end(); ++it)
         {
-            case attribute_t::hex:
-            case attribute_t::compress:
-                ss << ')';
-                break;
-            case attribute_t::primary_key:
-                break;
+            switch(*it)
+            {
+                case attribute_t::hex:
+                case attribute_t::compress:
+                case attribute_t::primary_key:
+                    ss << ')';
+                    break;
+            }
         }
+        convert_to_close = ss.str();
     }
-    return ss.str();
-}
 
-std::string field_t::convert_from_open() const
-{
-    std::ostringstream ss;
-    for (auto it = this->attributes.rbegin(); it != this->attributes.rend(); ++it)
+    /* convert_from_open */
     {
-        switch(*it)
+        std::ostringstream ss;
+        for (auto it = this->attributes.rbegin(); it != this->attributes.rend(); ++it)
         {
-            case attribute_t::hex:
-                ss << "UNHEX(";
-                break;
-            case attribute_t::compress:
-                ss << "UNCOMPRESS(";
-                break;
-            case attribute_t::primary_key:
-                break;
+            switch(*it)
+            {
+                case attribute_t::hex:
+                    ss << "UNHEX(";
+                    break;
+                case attribute_t::compress:
+                    ss << "UNCOMPRESS(";
+                    break;
+                case attribute_t::primary_key:
+                    ss << "BinToUuid(";
+                    break;
+            }
         }
+        convert_from_open = ss.str();
     }
-    return ss.str();
-}
 
-std::string field_t::convert_from_close() const
-{
-    std::ostringstream ss;
-    for (auto it = this->attributes.rbegin(); it != this->attributes.rend(); ++it)
+    /* convert_from_close */
     {
-        switch(*it)
+        std::ostringstream ss;
+        for (auto it = this->attributes.rbegin(); it != this->attributes.rend(); ++it)
         {
-            case attribute_t::hex:
-            case attribute_t::compress:
-                ss << ')';
-                break;
-            case attribute_t::primary_key:
-                break;
+            switch(*it)
+            {
+                case attribute_t::hex:
+                case attribute_t::compress:
+                case attribute_t::primary_key:
+                    ss << ')';
+                    break;
+            }
         }
+        convert_from_close = ss.str();
     }
-    return ss.str();
-}
\ No newline at end of file
+}
+
+#define throw_not_implemented(p_ret, p_name, ...)               \
+    p_ret field_t::p_name(__VA_ARGS__) const                    \
+    {                                                           \
+        throw misc::hibernate_exception(                        \
+            std::string("'") + table_name + "." + field_name +  \
+            "' does not implement the " #p_name "() method!");  \
+    }
+
+/* CRUD */
+
+throw_not_implemented(value_t,  foreign_create_update, const create_update_context&)
+
+/* properties */
+
+throw_not_implemented(bool,     is_default, const data_context& context)
+throw_not_implemented(string,   generate_value, ::cppmariadb::connection&)
+throw_not_implemented(value_t,  get, const data_context& context)
+throw_not_implemented(void,     set, const data_context& context, const value_t&)
\ No newline at end of file
diff --git a/src/driver/mariadb/schema/schema.cpp b/src/driver/mariadb/schema/schema.cpp
index 74358ed..a4a891b 100644
--- a/src/driver/mariadb/schema/schema.cpp
+++ b/src/driver/mariadb/schema/schema.cpp
@@ -13,7 +13,7 @@ using namespace ::cpphibernate::driver::mariadb_impl;
 
 void schema_t::update()
 {
-// clear everything
+    // clear everything
     for (auto& kvp : tables)
     {
         assert(static_cast<bool>(kvp.second));
@@ -25,6 +25,13 @@ void schema_t::update()
         table.foreign_table_one_fields.clear();
         table.foreign_table_many_fields.clear();
         table.data_fields.clear();
+
+        for (auto& ptr : table.fields)
+        {
+            assert(ptr);
+            auto& field = *ptr;
+            field.update();
+        }
     }
 
     // update references
@@ -54,12 +61,12 @@ void schema_t::update()
             auto& field = *ptr;
 
             // table
-            if (table.dataset_id != field.table_dataset_id)
+            if (table.dataset_id != field.dataset_id)
                 throw misc::hibernate_exception(std::string("dataset id of field '") + field.table_name + '.' + field.field_name + "' does not match!");
             field.table = &table;
 
             // referenced table
-            it = tables.find(field.value_dataset_id);
+            it = tables.find(field.real_value_id);
             auto referenced_table = (it != tables.end()
                 ? it->second.get()
                 : nullptr);
@@ -120,6 +127,23 @@ const table_t& schema_t::table(size_t dataset_id) const
     return *it->second;
 }
 
+const field_t& schema_t::field(size_t field_id) const
+{
+    for (auto& kvp : tables)
+    {
+        assert(kvp.second);
+        auto& table = *kvp.second;
+        for (auto& ptr : table.fields)
+        {
+            assert(ptr);
+            auto& field = *ptr;
+            if (field.id == field_id)
+                return field;
+        }
+    }
+    throw misc::hibernate_exception(std::string("unable to find field with id ") + std::to_string(field_id));
+}
+
 #define exec_query()                                                \
     do {                                                            \
         cpphibernate_debug_log("execute init query: " << ss.str()); \
diff --git a/src/driver/mariadb/schema/table.cpp b/src/driver/mariadb/schema/table.cpp
index 8a8ef0d..4135e8a 100644
--- a/src/driver/mariadb/schema/table.cpp
+++ b/src/driver/mariadb/schema/table.cpp
@@ -30,12 +30,12 @@ std::string build_init_stage1_query(const table_t& table)
     {
         assert(table.primary_key_field);
         auto& key_info = *table.primary_key_field;
-        auto  args     = key_info.create_table_arguments();
+        auto  args     = key_info.create_arguments;
         os  <<  indent
             <<  "`"
             <<  key_info.field_name
             <<  "` "
-            <<  key_info.type()
+            <<  key_info.type
             <<  " NOT NULL"
             <<  (args.empty() ? "" : " ")
             <<  args
@@ -52,7 +52,7 @@ std::string build_init_stage1_query(const table_t& table)
             <<  "`"
             <<  key_info.field_name
             <<  "` "
-            <<  key_info.type()
+            <<  key_info.type
             <<  " NOT NULL,";
     }
 
@@ -70,7 +70,7 @@ std::string build_init_stage1_query(const table_t& table)
             <<  "_id_"
             <<  field_info.field_name
             <<  "` "
-            <<  ref_key_info.type()
+            <<  ref_key_info.type
             <<  (field_info.value_is_nullable
                     ? " NULL DEFAULT NULL,"
                     : " NOT NULL,");
@@ -90,8 +90,17 @@ std::string build_init_stage1_query(const table_t& table)
             <<  "_id_"
             <<  field_info.field_name
             <<  "` "
-            <<  ref_key_info.type()
+            <<  ref_key_info.type
             <<  " NULL DEFAULT NULL,";
+        if (field_info.value_is_ordered)
+        {
+            os  <<  indent
+                <<  "`"
+                <<  field_info.table_name
+                <<  "_index_"
+                <<  field_info.field_name
+                <<  "` UNSIGNED INT NOT NULL,";
+        }
     }
 
     /* data fields */
@@ -103,7 +112,7 @@ std::string build_init_stage1_query(const table_t& table)
             <<  "`"
             <<  field_info.field_name
             <<  "` "
-            <<  field_info.type()
+            <<  field_info.type
             <<  (field_info.value_is_nullable
                     ? " NULL DEFAULT NULL,"
                     : " NOT NULL,");
@@ -353,18 +362,18 @@ std::string build_create_update_query(const table_t& table, const filter_t* filt
     {
         assert(table.primary_key_field);
         auto& key_info = *table.primary_key_field;
-        if (!key_info.is_auto_generated())
+        if (!key_info.value_is_auto_incremented)
         {
             if (index++)
                 os << ", ";
             os  <<  "`"
                 <<  key_info.field_name
                 <<  "`="
-                <<  key_info.convert_to_open()
+                <<  key_info.convert_to_open
                 <<  "?"
                 <<  key_info.field_name
                 <<  "?"
-                <<  key_info.convert_to_close();
+                <<  key_info.convert_to_close;
         }
     }
 
@@ -381,11 +390,11 @@ std::string build_create_update_query(const table_t& table, const filter_t* filt
         os  <<  "`"
             <<  key_info.field_name
             <<  "`="
-            <<  key_info.convert_to_open()
+            <<  key_info.convert_to_open
             <<  "?"
             <<  key_info.field_name
             <<  "?"
-            <<  key_info.convert_to_close();
+            <<  key_info.convert_to_close;
     }
 
     /* foreign table one fields */
@@ -405,13 +414,13 @@ std::string build_create_update_query(const table_t& table, const filter_t* filt
             <<  "_id_"
             <<  field_info.field_name
             <<  "`="
-            <<  key_info.convert_to_open()
+            <<  key_info.convert_to_open
             <<  "?"
             <<  key_info.table_name
             <<  "_id_"
             <<  field_info.field_name
             <<  "?"
-            <<  key_info.convert_to_close();
+            <<  key_info.convert_to_close;
     }
 
     /* foreign fields */
@@ -431,13 +440,23 @@ std::string build_create_update_query(const table_t& table, const filter_t* filt
             <<  "_id_"
             <<  field_info.field_name
             <<  "`="
-            <<  key_info.convert_to_open()
+            <<  key_info.convert_to_open
             <<  "?"
             <<  field_info.table_name
             <<  "_id_"
             <<  field_info.field_name
             <<  "?"
-            <<  key_info.convert_to_close();
+            <<  key_info.convert_to_close;
+        if (field_info.value_is_ordered)
+        {
+            if (index++)
+            os << ", ";
+            os  <<  "`"
+                <<  field_info.table_name
+                <<  "_index_"
+                <<  field_info.field_name
+                <<  "`=?\?";
+        }
     }
 
     /* data fields */
@@ -452,11 +471,11 @@ std::string build_create_update_query(const table_t& table, const filter_t* filt
         os  <<  "`"
             <<  field_info.field_name
             <<  "`="
-            <<  field_info.convert_to_open()
+            <<  field_info.convert_to_open
             <<  "?"
             <<  field_info.field_name
             <<  "?"
-            <<  field_info.convert_to_close();
+            <<  field_info.convert_to_close;
     }
 
     /* type field for derived tables */
@@ -476,11 +495,11 @@ std::string build_create_update_query(const table_t& table, const filter_t* filt
         os  <<  " WHERE `"
             <<  key_info.field_name
             <<  "`="
-            <<  key_info.convert_to_open()
+            <<  key_info.convert_to_open
             <<  "?"
             <<  key_info.field_name
             <<  "?"
-            <<  key_info.convert_to_close();
+            <<  key_info.convert_to_close;
     }
 
     return os.str();
@@ -503,7 +522,7 @@ std::string table_t::execute_create_update(
 
     /* primary key */
     assert(primary_key_field);
-    if (   !primary_key_field->is_auto_generated()
+    if (   !primary_key_field->value_is_auto_incremented
         && !is_update)
     {
         primary_key = primary_key_field->generate_value(context.connection);
@@ -550,15 +569,28 @@ std::string table_t::execute_create_update(
         if (is_update && ptr != context.owner_field)
             continue;
 
-        if (    context.owner_field
-            &&  ptr == context.owner_field)
+        auto& field_info = *ptr;
+        bool set_value =
+                context.owner_field
+            &&  ptr == context.owner_field;
+
+        if (set_value)
         {
             assert(!context.owner_key.empty());
             statement.set(index, context.owner_key);
         }
         else
+        {
             statement.set_null(index);
+        }
         ++index;
+
+        if (field_info.value_is_ordered)
+        {
+            if (set_value)  statement.set(index, context.index);
+            else            statement.set(index, 0);
+            ++index;
+        }
     }
 
     /* data fields */
@@ -604,7 +636,7 @@ std::string table_t::execute_create_update(
         cpphibernate_debug_log("execute UPDATE query: " << statement.query(connection));
     }
 
-    if (    primary_key_field->is_auto_generated()
+    if (    primary_key_field->value_is_auto_incremented
         && !is_update)
     {
         auto id = connection.execute_id(statement);
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index b995878..9205f24 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -12,6 +12,7 @@ Set                         ( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${PEDANTIC_CXX
 
 Project                     ( test_cpphibernate )
 File                        ( GLOB_RECURSE SOURCE_FILES ${CMAKE_CURRENT_SOURCE_DIR}/*.cpp )
+List                        ( FILTER SOURCE_FILES EXCLUDE REGEX "/_[A-Za-z0-9_-]*\.cpp$" )
 Add_Executable              ( test_cpphibernate EXCLUDE_FROM_ALL ${SOURCE_FILES} )
 Target_Link_Libraries       (
                                 test_cpphibernate
diff --git a/test/cpphibernate_create.cpp b/test/cpphibernate_create.cpp
index a864dc9..a100dca 100644
--- a/test/cpphibernate_create.cpp
+++ b/test/cpphibernate_create.cpp
@@ -103,7 +103,9 @@ TEST(CppHibernateTests, create_test3)
                         "SET "
                             "`tbl_test3_id`=UuidToBin('X3d12737a-abb9-11e8-98d0-529269fb1459X'), "
                             "`tbl_derived3_id_test3_list`=UuidToBin(null), "
+                            "`tbl_derived3_index_test3_list`='X0X', "
                             "`tbl_derived3_id_test3_vector`=UuidToBin(null), "
+                            "`tbl_derived3_index_test3_vector`='X0X', "
                             "`u32_data`='X5X', "
                             "`i32_data`='X6X', "
                             "`u64_data`='X7X', "
@@ -325,7 +327,9 @@ TEST(CppHibernateTests, create_derived3)
                         "SET "
                             "`tbl_test3_id`=UuidToBin('X3d1289f0-abb9-11e8-98d0-529269fb1459X'), "
                             "`tbl_derived3_id_test3_list`=UuidToBin('X3d12866c-abb9-11e8-98d0-529269fb1459X'), "
+                            "`tbl_derived3_index_test3_list`='X0X', "
                             "`tbl_derived3_id_test3_vector`=UuidToBin(null), "
+                            "`tbl_derived3_index_test3_vector`='X0X', "
                             "`u32_data`='X100X', "
                             "`i32_data`='X101X', "
                             "`u64_data`='X102X', "
@@ -340,7 +344,9 @@ TEST(CppHibernateTests, create_derived3)
                         "SET "
                             "`tbl_test3_id`=UuidToBin('X3d128b26-abb9-11e8-98d0-529269fb1459X'), "
                             "`tbl_derived3_id_test3_list`=UuidToBin('X3d12866c-abb9-11e8-98d0-529269fb1459X'), "
+                            "`tbl_derived3_index_test3_list`='X1X', "
                             "`tbl_derived3_id_test3_vector`=UuidToBin(null), "
+                            "`tbl_derived3_index_test3_vector`='X0X', "
                             "`u32_data`='X110X', "
                             "`i32_data`='X111X', "
                             "`u64_data`='X112X', "
@@ -355,11 +361,13 @@ TEST(CppHibernateTests, create_derived3)
                         "SET "
                             "`tbl_test3_id`=UuidToBin('X3d128eb4-abb9-11e8-98d0-529269fb1459X'), "
                             "`tbl_derived3_id_test3_list`=UuidToBin(null), "
+                            "`tbl_derived3_index_test3_list`='X0X', "
                             "`tbl_derived3_id_test3_vector`=UuidToBin('X3d12866c-abb9-11e8-98d0-529269fb1459X'), "
-                            "`u32_data`='X120X', "
-                            "`i32_data`='X121X', "
-                            "`u64_data`='X122X', "
-                            "`i64_data`='X123X'",
+                            "`tbl_derived3_index_test3_vector`='X0X', "
+                            "`u32_data`='X200X', "
+                            "`i32_data`='X201X', "
+                            "`u64_data`='X202X', "
+                            "`i64_data`='X203X'",
                         result_affected_rows(1));
 
     expect_query(mock,  "SELECT Uuid()", result_used({
@@ -370,11 +378,13 @@ TEST(CppHibernateTests, create_derived3)
                         "SET "
                             "`tbl_test3_id`=UuidToBin('X3d128ffe-abb9-11e8-98d0-529269fb1459X'), "
                             "`tbl_derived3_id_test3_list`=UuidToBin(null), "
+                            "`tbl_derived3_index_test3_list`='X0X', "
                             "`tbl_derived3_id_test3_vector`=UuidToBin('X3d12866c-abb9-11e8-98d0-529269fb1459X'), "
-                            "`u32_data`='X130X', "
-                            "`i32_data`='X131X', "
-                            "`u64_data`='X132X', "
-                            "`i64_data`='X133X'",
+                            "`tbl_derived3_index_test3_vector`='X1X', "
+                            "`u32_data`='X210X', "
+                            "`i32_data`='X211X', "
+                            "`u64_data`='X212X', "
+                            "`i64_data`='X213X'",
                         result_affected_rows(1));
 
     expect_query(mock,  "SELECT Uuid()", result_used({
@@ -385,11 +395,13 @@ TEST(CppHibernateTests, create_derived3)
                         "SET "
                             "`tbl_test3_id`=UuidToBin('X3d129134-abb9-11e8-98d0-529269fb1459X'), "
                             "`tbl_derived3_id_test3_list`=UuidToBin(null), "
+                            "`tbl_derived3_index_test3_list`='X0X', "
                             "`tbl_derived3_id_test3_vector`=UuidToBin('X3d12866c-abb9-11e8-98d0-529269fb1459X'), "
-                            "`u32_data`='X140X', "
-                            "`i32_data`='X141X', "
-                            "`u64_data`='X142X', "
-                            "`i64_data`='X143X'",
+                            "`tbl_derived3_index_test3_vector`='X2X', "
+                            "`u32_data`='X220X', "
+                            "`i32_data`='X221X', "
+                            "`u64_data`='X222X', "
+                            "`i64_data`='X223X'",
                         result_affected_rows(1));
 
     expect_query(mock,  "COMMIT");
@@ -418,20 +430,20 @@ TEST(CppHibernateTests, create_derived3)
     d3.test3_list.back().u64_data = 112;
     d3.test3_list.back().i64_data = 113;
     d3.test3_vector.emplace_back();
-    d3.test3_vector.back().u32_data = 120;
-    d3.test3_vector.back().i32_data = 121;
-    d3.test3_vector.back().u64_data = 122;
-    d3.test3_vector.back().i64_data = 123;
+    d3.test3_vector.back().u32_data = 200;
+    d3.test3_vector.back().i32_data = 201;
+    d3.test3_vector.back().u64_data = 202;
+    d3.test3_vector.back().i64_data = 203;
     d3.test3_vector.emplace_back();
-    d3.test3_vector.back().u32_data = 130;
-    d3.test3_vector.back().i32_data = 131;
-    d3.test3_vector.back().u64_data = 132;
-    d3.test3_vector.back().i64_data = 133;
+    d3.test3_vector.back().u32_data = 210;
+    d3.test3_vector.back().i32_data = 211;
+    d3.test3_vector.back().u64_data = 212;
+    d3.test3_vector.back().i64_data = 213;
     d3.test3_vector.emplace_back();
-    d3.test3_vector.back().u32_data = 140;
-    d3.test3_vector.back().i32_data = 141;
-    d3.test3_vector.back().u64_data = 142;
-    d3.test3_vector.back().i64_data = 143;
+    d3.test3_vector.back().u32_data = 220;
+    d3.test3_vector.back().i32_data = 221;
+    d3.test3_vector.back().u64_data = 222;
+    d3.test3_vector.back().i64_data = 223;
 
     ::cppmariadb::connection connection(reinterpret_cast<MYSQL*>(0x1111));
     auto context = make_context<driver::mariadb>(test_schema, connection);
diff --git a/test/cpphibernate_init.cpp b/test/cpphibernate_init.cpp
index 866660d..48f0fce 100644
--- a/test/cpphibernate_init.cpp
+++ b/test/cpphibernate_init.cpp
@@ -79,7 +79,9 @@ TEST(CppHibernateTests, init)
                         "(\n"
                         "    `tbl_test3_id` BINARY(16) NOT NULL,\n"
                         "    `tbl_derived3_id_test3_list` BINARY(16) NULL DEFAULT NULL,\n"
+                        "    `tbl_derived3_index_test3_list` UNSIGNED INT NOT NULL,\n"
                         "    `tbl_derived3_id_test3_vector` BINARY(16) NULL DEFAULT NULL,\n"
+                        "    `tbl_derived3_index_test3_vector` UNSIGNED INT NOT NULL,\n"
                         "    `u32_data` INT UNSIGNED NOT NULL,\n"
                         "    `i32_data` INT NOT NULL,\n"
                         "    `u64_data` BIGINT UNSIGNED NOT NULL,\n"
diff --git a/test/cpphibernate_read.cpp b/test/cpphibernate_read.cpp
new file mode 100644
index 0000000..5aa523e
--- /dev/null
+++ b/test/cpphibernate_read.cpp
@@ -0,0 +1,34 @@
+#include <cpphibernate/driver/mariadb.h>
+
+#include "test_helper.h"
+#include "test_schema.h"
+#include "mariadb_mock.h"
+
+using namespace ::testing;
+using namespace ::cpphibernate;
+
+TEST(CppHibernateTests, read_test1)
+{
+    StrictMock<mariadb_mock> mock;
+
+    // expect_query(mock,  "START TRANSACTION");
+    // expect_query(mock,  "COMMIT");
+
+    EXPECT_CALL(
+        mock,
+        mysql_close(
+            reinterpret_cast<MYSQL*>(0x1111)));
+
+    EXPECT_CALL(
+        mock,
+        mysql_real_escape_string(reinterpret_cast<MYSQL*>(0x1111), _, _, _))
+            .Times(AnyNumber())
+            .WillRepeatedly(WithArgs<1, 2, 3>(EscapeString()));
+
+    test1 t1;
+    t1.id = uuid("1e133ad8-ad2e-11e8-98d0-529269fb1459");
+
+    ::cppmariadb::connection connection(reinterpret_cast<MYSQL*>(0x1111));
+    auto context = make_context<driver::mariadb>(test_schema, connection);
+    context.read(t1);
+}
\ No newline at end of file