public static function retrieveByPK($pk, PropelPDO $con = null)
    {

        if (null !== ($obj = UserCustomerRelationPeer::getInstanceFromPool((string) $pk))) {
            return $obj;
        }

        if ($con === null) {
            $con = Propel::getConnection(UserCustomerRelationPeer::DATABASE_NAME, Propel::CONNECTION_READ);
        }

        $criteria = new Criteria(UserCustomerRelationPeer::DATABASE_NAME);
        $criteria->add(UserCustomerRelationPeer::ID, $pk);

        $v = UserCustomerRelationPeer::doSelect($criteria, $con);

        return !empty($v) > 0 ? $v[0] : null;
    }