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

        return $this->addUsingAlias(DealerTableMap::ZIPCODE, $zipcode, $comparison);
    }