Question

我需要一个日期递减的SQL查询循环。

StartDate : 3/15/2015    [Date param] [MM/dd/yyyy]
EndDate   : 3/5/2015     [Date param]  
Operation : Decrement by a day toward EndDate
BreakDate : 3/10/2015    [Date param]

当前日期（循环中）应从开始日期到结束日期打印一天减量

如果达到中断日期，那么循环应该自行停止[内循环]

输入上面的示例结果：

请帮助。

Answer 1

您不需要循环。您应该从不以这种心态处理SQL中的问题，它应该是最后的手段。

如果使用日期，那么最简单的解决方案是使用calendar table，如果你没有创建一个，那么你可以使用：

DECLARE @StartDate DATE = '20150315',
        @EndDate DATE = '20150305',
        @BreakDate DATE = '20150310';

SELECT  Date
FROM    Calendar
WHERE   Date <= @StartDate
AND     Date > @EndDate
AND     Date > @BreakDate;

但是，我很欣赏创建日历表并不总是一个选项，但可以很容易地生成日期列表。来自以下文章：

动态执行此操作的最佳方法是使用常量的交叉连接（文章中称为Stacked CTE）。这只是从一个10行的表值构造函数开始，交叉连接到它自己获得100行，然后再次获得100x100 = 10,000行，依此类推：

DECLARE @StartDate DATE = '20150315',
        @EndDate DATE = '20150305',
        @BreakDate DATE = '20150310';

WITH N1 (N) AS (SELECT 1 FROM (VALUES (1), (1), (1), (1), (1), (1), (1), (1), (1), (1)) n (N)),
N2 (N) AS (SELECT 1 FROM N1 AS N1 CROSS JOIN N1 AS N2),
N3 (N) AS (SELECT 1 FROM N2 AS N1 CROSS JOIN N2 AS N2),
N4 (N) AS (SELECT ROW_NUMBER() OVER(ORDER BY N1.N) FROM N3 AS N1 CROSS JOIN N3 AS N2)
SELECT  Date = DATEADD(DAY, 1 - N, @StartDate)
FROM    N4
WHERE   N <= DATEDIFF(DAY, @EndDate, @StartDate) + 1
AND     N <= DATEDIFF(DAY, @BreakDate, @StartDate) + 1;

修改

如果您的休息日期可以在开始日期之后，那么您只需要一些额外的逻辑来解决这个问题，因此您的查询将变为：

DECLARE @StartDate DATE = '20150315', @EndDate DATE = '20150305', @BreakDate DATE = '20150310'; SELECT Date FROM Calendar WHERE Date <= @StartDate AND Date > @EndDate AND ( Date > @BreakDate OR @BreakDate >= @StartDate );

或者

DECLARE @StartDate DATE = '20150315', @EndDate DATE = '20150305', @BreakDate DATE = '20150320'; WITH N1 (N) AS (SELECT 1 FROM (VALUES (1), (1), (1), (1), (1), (1), (1), (1), (1), (1)) n (N)), N2 (N) AS (SELECT 1 FROM N1 AS N1 CROSS JOIN N1 AS N2), N3 (N) AS (SELECT 1 FROM N2 AS N1 CROSS JOIN N2 AS N2), N4 (N) AS (SELECT ROW_NUMBER() OVER(ORDER BY N1.N) FROM N3 AS N1 CROSS JOIN N3 AS N2) SELECT Date = DATEADD(DAY, 1 - N, @StartDate) FROM N4 WHERE N <= DATEDIFF(DAY, @EndDate, @StartDate) + 1 AND ( N <= DATEDIFF(DAY, @BreakDate, @StartDate) + 1 OR @BreakDate >= @StartDate );

Answer 2

此解决方案限制为2048天，但可以使用不同的计数进行扩展：

SELECT cast(dateadd(day, -number, @startdate) as date) date
FROM master..spt_values
WHERE 
  type = 'P' 
  AND dateadd(day, -number, @StartDate) >= @EndDate
  AND @BreakDate NOT BETWEEN dateadd(day, 1 - number, @StartDate) AND @startdate

Answer 3

作业？ ;）

DECLARE @dateStart SMALLDATETIME = '20150315'
DECLARE @dateEnd SMALLDATETIME = '20150305'
DECLARE @dateBreak SMALLDATETIME = '20150310'

WHILE (@dateStart>@dateEnd)
    BEGIN
        print @dateStart;
        IF (@dateStart=@dateBreak) BREAK
        SET @dateStart-=1
    END

Answer 4

您可以通过WHILE循环执行此操作。但在开始循环之前，请考虑RBAR。

这将按预期给出准确的输出。

DECLARE @FromDate DATE = '3/15/2015', 
        @EndDate DATE = '3/5/2015',
        @BreakDate DATE = '3/10/2015' 

WHILE (@FromDate >= @endDate)
BEGIN
    PRINT @FromDate

    -- Perform your operations here

    IF(@FromDate = @BreakDate)
        Break;

    --Incrementing to next date
    SELECT @FromDate = DATEADD(DAY, -1, @FromDate)
END
GO

我需要一个sql查询循环，日期减少一天，直到休息日期

4 个答案: