public function generateQueries(array $diff_res)
    {
        $queries = array();
        foreach ($diff_res[self::ADD] as $new_field) {
            $queries[] = $this->createAddQuery($new_field);
        }
        foreach ($diff_res[self::DEL] as $del_field) {
            $queries[] = $this->createDeleteQuery($del_field);
        }
        foreach ($diff_res[self::UPDATE] as $mod_field) {
            $queries[] = $this->createUpdateQuery($mod_field);
        }
        return $queries;
    }