public function filterByKey($key = null, $comparison = null)
    {
        if (null === $comparison) {
            if (is_array($key)) {
                $comparison = Criteria::IN;
            } elseif (preg_match('/[\%\*]/', $key)) {
                $key = str_replace('*', '%', $key);
                $comparison = Criteria::LIKE;
            }
        }

        return $this->addUsingAlias(SystemSettingsPeer::KEY, $key, $comparison);
    }