protected function _getOrderField() {
		$orderList = $this->_getOrderList();
		$result = null;
		foreach ($orderList as $orderField) {
			if (!$this->hasField($orderField)) {
				continue;
			}

			$result = $orderField;
			break;
		}

		return $result;
	}
protected function _getOrderField() {
		$orderList = $this->_getOrderList();
		$result = null;
		foreach ($orderList as $orderField) {
			if (!$this->hasField($orderField)) {
				continue;
			}

			$result = $orderField;
			break;
		}

		return $result;
	}
protected function _getOrderField ( ) { $ orderList = $ this -> _getOrderList ( ) ; $ result = null ; foreach ( $ orderList as $ orderField ) { if ( ! $ this -> hasField ( $ orderField ) ) { continue ; } $ result = $ orderField ; break ; } return $ result ; }
Return field for ordering data

@return string|null Return field for ordering data, or Null.
Return field for ordering data