sql - SQL INSERT 计算日期之间的 NoOfDays

Question

    CREATE TABLE "Reservation"(

    ReservationID int IDENTITY (1,1) NOT NULL,
    CustomerID int NOT NULL,
    RoomNo int NOT NULL,
    CheckInDate date NULL,
    CheckOutDate date NULL,
    NoOfDays int NULL,

    CONSTRAINT PK_Reservation PRIMARY KEY(ReservationID),

    CONSTRAINT FK_Reservation_Customers_CustID FOREIGN KEY(CustomerID)  
        REFERENCES dbo.Customers(CustomerID),

    CONSTRAINT FK_Reservation_Rooms_RoomNo FOREIGN KEY(RoomNo)
        REFERENCES dbo.Rooms(RoomNo)
)


INSERT Reservation(CustomerID,RoomNo,CheckInDate,CheckOutDate,NoOfDays)
        VALUES(1,101,'2012-01-01','2012-01-30',DATEDIFF(NoOfDays,'CheckInDate','CheckOutDate'))

有人可以告诉我如何计算“CheckInDate”和“CheckOutDate”之间的天数，然后在 NoOfDays 的插入语句中使用这个值。很难解释我希望你明白我在这里想要达到的目标。

Answer 1

更新：

试试这个：

INSERT Reservation(CustomerID,RoomNo,CheckInDate,CheckOutDate,NoOfDays)
    VALUES(1,101,'2012-01-01','2012-01-30',DATEDIFF(day,'2012-01-01','2012-01-30'));

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