Algo-Web / POData

        $key = rtrim($key, ' and ');

        if ($srcClass === 'Customer') {

            if ($navigationPropName === 'Orders') {

                $query = "SELECT * FROM Orders WHERE CustomerID = '$sourceEntityInstance->CustomerID' and $key";

                $stmt = sqlsrv_query($this->_connectionHandle, $query);

                if ($stmt === false) {

                    $errorAsString = self::_getSQLSRVError();

                    throw ODataException::createInternalServerError($errorAsString);

                }

                $result = $this->_serializeOrders($stmt);

            } else {

                die('Customer does not have navigation porperty with name: ' . $navigationPropName);

            }

        } elseif ($srcClass === 'Order') {

            if ($navigationPropName === 'Order_Details') {

                $query = "SELECT * FROM [Order Details] WHERE OrderID = $sourceEntityInstance->OrderID";

            } else {

                die('Customer does not have navigation porperty with name: ' . $navigationPropName);

            }

        } elseif ($srcClass === 'Order') {

            if ($navigationPropName === 'Order_Details') {

                $query = "SELECT * FROM [Order Details] WHERE OrderID = $sourceEntityInstance->OrderID";

                $stmt = sqlsrv_query($this->_connectionHandle, $query);

                if ($stmt === false) {

                    $errorAsString = self::_getSQLSRVError();

                    throw ODataException::createInternalServerError($errorAsString);

                }

                $result = $this->_serializeOrderDetails($stmt);

            } else {

                die('Order does not have navigation porperty with name: ' . $navigationPropName);

            }

        }

        return empty($result) ? null : $result[0];

    }