SQL Server:确定两个日期之间的年、月、周和日

问题描述

阅读本主题并被建议使用 DateDiff 后.我写了一个没有提供我想要的答案的函数.客户现在想知道完成清单需要多长时间.我有一个 CreationDate 和 CompletionDate.我需要知道花了多少年、月、周和天.如果是 2 天，则是没有年份的2 天".该函数减去年数，然后尝试检查月数，然后是周数，然后是天数.如果可用，只给出结果.似乎 DateDiff 是问题所在……或者我是不理解 DateDiff 的问题.它甚至返回一个星期，因为日期相差 4 天，这是没有意义的.它应该返回两个日期内的周数，而不关心它何时开始.

After reading on this topic and being advised to use DateDiff. I wrote a function that doesn't provide the answer I want. The client wants to now how long it took to complete a checklist. I have a CreationDate and CompletionDate. I need to know how many years, months, weeks and days it took. If it is 2 days then '2 days' without the years. The function deducts the number of years and then attempt to check the number of months, then the number of weeks and then the number of days. Only results are given if available. It seems DateDiff is the problem... or I am the problem not understanding DateDiff. It even returns a week for a 4 day difference in dates which doesn't make sense. It should return the number of weeks within the two dates, not caring when it starts.

这是代码

ALTER FUNCTION [dbo].[DateRangeText]
    (@FromDate DATETIME, @ToDate DATETIME)
RETURNS VARCHAR(MAX)
AS
BEGIN
    DECLARE @Result AS VARCHAR(MAX);
    SET @Result = '';

    DECLARE @TmpS AS VARCHAR(MAX);
    SET @TmpS = '';

    DECLARE @Years AS INT;
    SET @Years = DATEDIFF(year, @FromDate, @ToDate);
    IF (@Years > 0)
    BEGIN
        IF (@Years = 1)
            SET @TmpS = ' Year ';
        ELSE
            SET @TmpS = ' Years ';

        SET @Result = @Result + CAST(@Years AS VARCHAR) + @TmpS;
        SET @ToDate = DATEADD(YEAR, -1 * @Years, @ToDate);
    END;

    DECLARE @Months AS INT;
    SET @Months = DATEDIFF(month, @FromDate, @ToDate);
    IF (@Months > 0)
    BEGIN
        IF (@Months = 1)
            SET @TmpS = ' Month ';
        ELSE
            SET @TmpS = ' Months ';

        SET @Result = @Result + CAST(@Months AS VARCHAR) + @TmpS;
        SET @ToDate = DATEADD(MONTH, -1 * @Months, @ToDate);
    END;

    DECLARE @Weeks AS INT;
    SET @Weeks = DATEDIFF(week, @FromDate, @ToDate);
    IF (@Weeks > 0)
    BEGIN
        IF (@Weeks = 1)
            SET @TmpS = ' Week ';
        ELSE
            SET @TmpS = ' Weeks ';

        SET @Result = @Result + CAST(@Weeks AS VARCHAR) + @TmpS;
        SET @ToDate = DATEADD(WEEK, -1 * @Weeks, @ToDate);
    END;

    DECLARE @Days AS INT;
    SET @Days = DATEDIFF(day, @FromDate, @ToDate);
    IF (@Days > 0)
    BEGIN
        IF (@Days = 1)
            SET @TmpS = ' Day ';
        ELSE
            SET @TmpS = ' Days ';

        SET @Result = @Result + CAST(@Days AS VARCHAR) + @TmpS;
        SET @ToDate = DATEADD(WEEK, -1 * @Days, @ToDate);
    END;

    IF (@Result = '')
        SET @Result = 'Same day';

    RETURN Rtrim(COALESCE(@Result,''));
END; 

推荐答案

由于您正在使用函数，请考虑以下表值函数.易于使用的单机版或作为 CROSS APPLY 包含在内.

Since you are using a function, consider the following Table-Valued Function. Easy to use a stand-alone or included as a CROSS APPLY.

高性能且准确，无需担心所有杂项日期计算.

Performant and Accurate without having to worry about all the misc date calculations.

示例

Select * from [dbo].[tvf-Date-Elapsed] ('1991-09-12 21:00:00.000',GetDate())

退货

Years   Months  Days    Hours   Minutes Seconds
26      7       5       13      47      11

感兴趣的TVF

CREATE FUNCTION [dbo].[tvf-Date-Elapsed] (@D1 DateTime,@D2 DateTime)
Returns Table
Return (
    with cteBN(N)   as (Select 1 From (Values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) N(N)),
         cteRN(R)   as (Select Row_Number() Over (Order By (Select NULL))-1 From cteBN a,cteBN b,cteBN c),
         cteYY(N,D) as (Select Max(R),Max(DateAdd(YY,R,@D1))From cteRN R Where DateAdd(YY,R,@D1)<=@D2),
         cteMM(N,D) as (Select Max(R),Max(DateAdd(MM,R,D))  From (Select Top 12 R From cteRN Order By 1) R, cteYY P Where DateAdd(MM,R,D)<=@D2),
         cteDD(N,D) as (Select Max(R),Max(DateAdd(DD,R,D))  From (Select Top 31 R From cteRN Order By 1) R, cteMM P Where DateAdd(DD,R,D)<=@D2),
         cteHH(N,D) as (Select Max(R),Max(DateAdd(HH,R,D))  From (Select Top 24 R From cteRN Order By 1) R, cteDD P Where DateAdd(HH,R,D)<=@D2),
         cteMI(N,D) as (Select Max(R),Max(DateAdd(MI,R,D))  From (Select Top 60 R From cteRN Order By 1) R, cteHH P Where DateAdd(MI,R,D)<=@D2),
         cteSS(N,D) as (Select Max(R),Max(DateAdd(SS,R,D))  From (Select Top 60 R From cteRN Order By 1) R, cteMI P Where DateAdd(SS,R,D)<=@D2)

    Select [Years]   = cteYY.N
          ,[Months]  = cteMM.N
          ,[Days]    = cteDD.N
          ,[Hours]   = cteHH.N
          ,[Minutes] = cteMI.N
          ,[Seconds] = cteSS.N
          --,[Elapsed] = Format(cteYY.N,'0000')+':'+Format(cteMM.N,'00')+':'+Format(cteDD.N,'00')+' '+Format(cteHH.N,'00')+':'+Format(cteMI.N,'00')+':'+Format(cteSS.N,'00')
     From  cteYY,cteMM,cteDD,cteHH,cteMI,cteSS
)
--Max 1000 years
--Select * from [dbo].[tvf-Date-Elapsed] ('1991-09-12 21:00:00.000',GetDate())
--Select * from [dbo].[tvf-Date-Elapsed] ('2017-01-01 20:30:15','2018-02-05 22:58:35')

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