protected function makeCharacteristicsDDL()
    {
        return implode(
            " ",
            array_filter(
                [
                    $this->deterministic ? 'DETERMINISTIC' : 'NOT DETERMINISTIC',
                    $this->dataAccess,
                    !empty($this->sqlSecurity) ? 'SQL SECURITY ' . $this->sqlSecurity : null,
                    !empty($this->comment) ? "\nCOMMENT '" . addslashes($this->comment) . "'" : null
                ]
            )
        );
    }