public function moveToBottom(ConnectionInterface $con = null)
    {
        if ($this->isLast($con)) {
            return false;
        }
        if (null === $con) {
            $con = Propel::getServiceContainer()->getWriteConnection(CustomerGroupTableMap::DATABASE_NAME);
        }
        $con->beginTransaction();
        try {
            $bottom = ChildCustomerGroupQuery::create()->getMaxRankArray($con);
            $res = $this->moveToRank($bottom, $con);
            $con->commit();

            return $res;
        } catch (Exception $e) {
            $con->rollback();
            throw $e;
        }
    }