Question

我正在为此功能获得正确的输出。 datediff是否仅计算同月的天数差异？当我以2015年1月1日及以后的形式通过约会时。它总是给我发回0 = /我错过了我的逻辑或语法中的东西吗？

CREATE FUNCTION dbo.CanPolicy
(
    @ReservationID int,
    @CancellationDate date
)
RETURNS smallmoney
AS
    BEGIN
        DECLARE @DepositPaid smallmoney
        SET @DepositPaid = (SELECT ResDepositPaid
                            FROM Reservation
                            WHERE ReservationID = @ReservationID)
        DECLARE @ResDate date
        SET @ResDate = (SELECT ResDate
                        FROM Reservation
                        WHERE ReservationID = @ReservationID)
        DECLARE @CanceledDaysAhead int
        SET @CanceledDaysAhead = DATEDIFF(day, @ResDate, @CancellationDate)
        DECLARE @result smallmoney
        SET @result = 0
        SET @result = CASE WHEN @CanceledDaysAhead > 30 THEN 0
                        WHEN @CanceledDaysAhead BETWEEN 14 AND 30 THEN @DepositPaid * 0.25 + 25
                        WHEN @CanceledDaysAhead BETWEEN 8 AND 13 THEN @DepositPaid * 0.50 + 25
                        ELSE @DepositPaid
                    END
        RETURN @result
    END

GO

Answer 1

不，DATEDIFF计算两者之间的日期。尝试：

SELECT DATEDIFF(day,{ts'2105-01-01 00:00:00'},{ts'2105-04-01 00:00:00'})

可能是日期格式问题......

您确定@ResDate设置正确吗？

编辑：CTE的新方法

DECLARE @ReservationID INT=123;
DECLARE @CancelationDate DATE=GETDATE();

WITH ReservationCTE AS
(
    SELECT ResDepositPaid 
          ,ResDate
    FROM Reservation
    WHERE ReservationID=@ReservationID --assuming that ReservationID is a unique key!
)
,ReservationCTEWithDateDiff AS
(
    SELECT ReservationCTE.*
          --EDIT: switched dates due to a comment by Me.Name
          ,DATEDIFF(DAY,@CancelationDate,ResDate) AS CanceledDaysAhead
    FROM ReservationCTE
)
SELECT CASE WHEN CanceledDaysAhead>30 THEN 0
            WHEN CanceledDaysAhead BETWEEN 14 AND 30 THEN ResDepositPaid * 0.25 + 25
            WHEN CanceledDaysAhead BETWEEN 8 AND 13 THEN ResDepositPaid * 0.50 + 25
            ELSE ResDepositPaid END AS MyReturnValue
FROM ReservationCTEWithDateDiff

Answer 2

我认为你的功能的正确和简短版本就是这个 - 请试一试：

CREATE FUNCTION dbo.CanPolicy
(
    @ReservationID int,
    @CancellationDate date
)
RETURNS smallmoney
AS
    BEGIN
        DECLARE @DepositPaid smallmoney,
                @CanceledDaysAhead int

        SELECT  @DepositPaid = ResDepositPaid,
                @CanceledDaysAhead = DATEDIFF(DAY,ResDate,@CancellationDate)
        FROM    Reservation
        WHERE   ReservationID = @ReservationID


        RETURN CAST(CASE WHEN @CanceledDaysAhead > 30 THEN 0 ELSE
               CASE WHEN @CanceledDaysAhead BETWEEN 14 AND 30 THEN @DepositPaid * 0.25 + 25 ELSE
               CASE WHEN @CanceledDaysAhead BETWEEN 8 AND 13 THEN @DepositPaid * 0.50 + 25 ELSE
               @DepositPaid END END END AS smallmoney)

    END
GO

主要问题是你的情况 - 当我认为阻止......

Answer 3

你现在可能已经解决了这个问题，但是我处理日期差异的一种方法是不使用差异为+或 - 值是使用ABS：

ABS on MSDN

这种情况下，case语句不需要区分它们。

TSQL计算的麻烦 - 日期差异给我带来麻烦

3 个答案: