FOREIGN_KEY约束异常

Question

我有一个带ac＃代码的asp.net应用程序，并使用linq-to-entities连接到SQL数据库...当我尝试对以下代码进行“ SaveChanges（）”时，出现异常（在下面列出）。 有什么想法吗？

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();                    
                }
            }
        }

例外情况：

UPDATE语句与FOREIGN KEY约束\\“ FK_Rides_Vehicles \\”冲突。 在数据库\\“ CWIS29RamRideOps \\”，表\\“ dbo.Vehicles \\”，“ Identity”列中发生了冲突。\\ r \\ n该语句已终止。

数据库：

Answer 1

这行：

assignedCar.Rides.Add(newRide);

被转换为SQL-INSERT-当您已经具有相同ID的记录时。 确定您要执行的操作：插入新游乐设施（在这种情况下，您应该将newRide的ID设为NULL）或更新（在这种情况下，您应该只注释掉该行；更改将被保存）。

Answer 2

像这样更改代码：

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();