FOREIGN_KEY約束異常

Question

我有一個帶ac＃代碼的asp.net應用程序，並使用linq-to-entities連接到SQL數據庫...當我嘗試對以下代碼進行“ SaveChanges（）”時，出現異常（在下面列出）。 有什么想法嗎？

private void setNewRide(long newRideID, int carNum)
        {
            handleCompletedRide(carNum);

            using (myEntities = new RamRideOpsEntities())
            {
                Vehicle assignedCar = myEntities.Vehicles.FirstOrDefault(car => car.CarNum == carNum);
                Ride newRide = myEntities.Rides.FirstOrDefault(ride => ride.identity == newRideID);

                if (assignedCar != null && newRide != null)
                {
                    vs_CurrentRideId = newRide.identity; //Save current ride to ViewState
                    vs_CarStatus = assignedCar.Status; //Save old status to ViewState

                    assignedCar.Status = "EnRoute";
                    assignedCar.CurrPassengers = newRide.NumPatrons;
                    assignedCar.StartAdd = newRide.PickupAddress;
                    assignedCar.EndAdd = newRide.DropoffAddress;
                    assignedCar.CurrentAdd = newRide.DropoffAddress;

                    assignedCar.Rides.Add(newRide);

                    newRide.TimeDispatched = DateTime.Now;
                    newRide.WaitTime = (((DateTime)newRide.TimeDispatched) - ((DateTime)newRide.TimeOfCall));
                    newRide.AssignedCar = carNum;
                    newRide.Status = "EnRoute";

                    myEntities.SaveChanges(); //EXCEPTION HERE!
                    SelectCarUP.DataBind();
                    SelectCarUP.Update();                    
                }
            }
        }

例外情況：

UPDATE語句與FOREIGN KEY約束\\“ FK_Rides_Vehicles \\”沖突。 在數據庫\\“ CWIS29RamRideOps \\”，表\\“ dbo.Vehicles \\”，“ Identity”列中發生了沖突。\\ r \\ n該語句已終止。

數據庫：

Answer 1

這行：

assignedCar.Rides.Add(newRide);

被轉換為SQL-INSERT-當您已經具有相同ID的記錄時。 確定您要執行的操作：插入新游樂設施（在這種情況下，您應該將newRide的ID設為NULL）或更新（在這種情況下，您應該只注釋掉該行；更改將被保存）。

Answer 2

像這樣更改代碼：

newRide.TimeDispatched = DateTime.Now;
newRide.WaitTime = (((DateTime)newRide.TimeDispatched) - ((DateTime)newRide.TimeOfCall));
newRide.AssignedCar = carNum;
newRide.Status = "EnRoute";

assignedCar.Status = "EnRoute";
assignedCar.CurrPassengers = newRide.NumPatrons;
assignedCar.StartAdd = newRide.PickupAddress;
assignedCar.EndAdd = newRide.DropoffAddress;
assignedCar.CurrentAdd = newRide.DropoffAddress;
assignedCar.Rides = newRide; // Your First Change here

myEntities.SaveChanges();