_setDbAdapter example

    public function __construct(Zend_Db_Adapter_Abstract $zendDb = null, $tableName = null, $identityColumn = null,
                                $credentialColumn = null, $credentialTreatment = null)
    {
        $this->_setDbAdapter($zendDb);

        if ($tableName !== null) {
            $this->setTableName($tableName);
        }

        if ($identityColumn !== null) {
            $this->setIdentityColumn($identityColumn);
        }

        if ($credentialColumn !== null) {
            $this->setCredentialColumn($credentialColumn);
        }