Question

我有开始日期＆amp;将Mdate作为表中的列，我想在SQL中执行类似下面的操作

将1个月添加到Start_Date，直到开始日期＆gt; Mdate

我尝试使用while和if概念，但没有运气。

DECLARE @MIGRATIONDATE DATE, @STRT_DATE DATE, @NEXTD DATE
SET @MIGRATIONDATE =20140725
SET @STRT_DATE = 20140521

SELECT WHILE ( @STRT_DATE > @MIGRATIONDATE)
         BEGIN 
             DATEADD(MM,1,@STRT_DATE))
         END

感谢你能指导我吗？

Answer 1

select 
     case when start_date<Mdate then dateadd(mm,1,start_date) else start_date end
   from yourTable

假设start_date是20140721而MigrationDate是20140525然后它返回给你接受的结果

select case 
        when convert( date,'20140721') <convert(date,'20140525')
         then dateadd(mm,1,'20140721') else '20140721' end

Answer 2

我不知道你是否想获得该表的一行。如果你想为每一行做，那么你应该将它包装在一个函数中并使用CROSS APPLY。

declare
@startdate datetime, 
@enddate datetime

set @startdate = '20140101'
set @enddate = '20150101'

;WITH date_range (thedate) AS (  
  select @startdate  
  UNION ALL SELECT DATEADD(MONTH, 1, thedate)  
            FROM date_range  
            WHERE DATEADD(MONTH, 1, thedate) <= @enddate  
            )  
SELECT  thedate FROM date_range

如果你想要一个功能：

CREATE FUNCTION [dbo].[ExplodeDates](@startdate datetime, @enddate datetime)
returns table as
return (

WITH date_range (thedate) AS (  
  select @startdate  
  UNION ALL SELECT DATEADD(DAY, 1, thedate)  
            FROM date_range  
            WHERE DATEADD(DAY, 1, thedate) <= @enddate  
            )  
SELECT  thedate FROM date_range   
);


SELECT Id,thedate
FROM   Table1 T1
       CROSS APPLY [dbo].[ExplodeDates](T1.StartDate,T1.EndDate)

Answer 3

如何（SQL Fiddle）：

SELECT DATEADD(month, 
               DATEDIFF(month, Start_Date, Mdate) + 1, 
               Start_Date) AS NEW_START_DATE
FROM MyTable;

如果Start_Date有可能大于或等于Mdate，请使用以下（SQL Fiddle）：

SELECT Start_Date AS OLD_START_DATE,
      CASE WHEN DATEDIFF(month, Start_Date, Mdate) > 0 
      THEN DATEADD(month, DATEDIFF(month, Start_Date, Mdate) + 1, Start_Date)
      ELSE Start_Date END  AS NEW_START_DATE,
      Mdate
FROM MyTable;

添加一个月，直到它大于某个值

3 个答案: