獲取前行的RefToDate成爲下一行的RefFromDate TSQL

我有對以下格式的數據表：獲取前行的RefToDate成爲下一行的RefFromDate TSQL

ProjID ProjName RefDate  
-------- ----------- ---------- 
1  A   08/02/2013 
1  A   08/03/2013 
1  A   08/15/2013 
2  B   08/02/2013 
2  B   08/03/2013 
2  B   08/15/2013 
2  B   08/20/2013

我想要一個結果，看起來象下面這樣：

ProjID ProjName StartDate EndDate  
-------- ----------- ---------- ------------ 
1  A   08/02/2013 08/02/2013 
1  A   08/02/2013 08/03/2013 
1  A   08/03/2013 08/15/2013 
2  B   08/02/2013 08/02/2013 
2  B   08/02/2013 08/16/2013 
2  B   08/16/2013 08/20/2013 
2  B   08/20/2013 08/22/2013

StartDate從上一行的refdate複製而來。

如何讓TSQL語句提出上述結果集？我可以做一個迭代，但它不是做IMHO的最佳方式。

來源

2013-08-28 user1505676

是有辦法找出明確地一桌子的一排？ –

你是什麼意思？一個唯一的列ID？ – user1505676

如果數據在表中未排序如何知道下一行是哪一行？ – Justin

如果您運行SQL2005或更高版本，可以

self join挑下一個日期
和union第一行對每個項目

是這樣的：

; 
WITH ProjectDataRanked 
     AS (SELECT ProjID , 
        ProjName , 
        RefDate , 
        ROW_NUMBER() OVER (PARTITION BY ProjID, ProjName ORDER BY RefDate) RN 
      FROM  ProjectData 
     ) 
SELECT ProjectData.ProjID , 
     ProjectData.ProjName , 
     ProjectData.RefDate AS StartDate , 
     MIN(ProjectDataNext.RefDate) AS EndDate 
FROM ProjectData 
     INNER JOIN ProjectData ProjectDataNext ON ProjectData.ProjID = ProjectDataNext.ProjID 
                AND ProjectData.ProjName = ProjectDataNext.ProjName 
                AND ProjectData.RefDate > ProjectDataNext.RefDate 
GROUP BY ProjectData.ProjID , 
     ProjectData.ProjName , 
     ProjectData.RefDate 
UNION 
SELECT ProjID , 
     ProjName , 
     RefDate AS StartDate , 
     RefDate AS EndDate 
FROM ProjectDataRanked 
WHERE RN = 1 
ORDER BY ProjID , 
     ProjName , 
     StartDate , 
     EndDate

來源

2013-08-28 04:52:40

SQL語句有效，但將ProjectData.RefDate> ProjectDataNext.RefDate更改爲ProjectData.RefDate user1505676

ups抱歉...錯誤的方向。 –

如果您使用的是SQL Server 2005/2008， n您可以試試這個

;with cte as 
(
    select *, 
    row_number() over (partition by projid order by refdate) rn 
    from projects 
) 
select c.projid, c.projname, 
coalesce(l.refdate, c.refdate) as startdate, 
c.refdate as enddate 
from cte c 
left outer join cte l 
    on c.projid = l.projid and (c.rn -1) = l.rn 
order by 1,3,4

SQL DEMO

SQL Server 2012的支持LAG功能，你可以用它來達到相同的結果

select 
c.projid, c.projname, 
coalesce(lag(c.refdate) 
     over (partition by projid 
       order by refdate),c.refdate) 
as startdate, 
c.refdate as enddate 
from projects c 
order by 1,3,4;

SQL DEMO for 2012

來源

2013-08-28 04:53:00

獲取前行的RefToDate成爲下一行的RefFromDate TSQL

回答

相關問題