public function dateTime($value, $type = NULL)
    {
        $apend = "";
        switch ($type) {
            case 'time':
                    $apend = 'time';
                break;
            case 'timestamp':
                    $apend = 'timestamp';
                break;
            case 'date':
                    $apend = 'date';
                break;
            case 'datetime':
                    $apend = 'datetime';
                break;
            case 'year':
                    $apend = 'year(4)';
                break;
            default:
                    $apend = 'timestamp';
                break;
        }
        return $value . " " . $apend . " NOT NULL";
    }