sql-server – 如何在不同的列中选择不同的行值

我有一张桌子.

ID  Date         Value
1   12/12/2014   A
1   24/12/2014   T
2   13/12/2014   A
2   23/12/2014   T
3   12/03/2014   A
3   12/04/2014   T
4   12/12/2014   T
5   12/04/2014   T

我想要结果,如ADate是值为A的日期,而TDate是值为T的日期

ID    ADate            TDate
1     12/12/2014      24/12/2014
2     13/12/2014      23/12/2014
3     12/03/2014      12/04/2014
4         -           12/12/2014
5         -           12/04/2014

解决方法

SELECT id,Min(CASE
             WHEN value = 'A' THEN [Date]
           END) Adate,Max(CASE
             WHEN value = 'T' THEN [Date]
           END) Tdate
FROM   Tablename
GROUP  BY id

更新：获取具有相同ID的行

DECLARE @cnt INT

SELECT TOP 1 @cnt = Count(1) / 2
FROM   #test
GROUP  BY id
ORDER  BY Count(1) / 2 DESC

SELECT id,Max(CASE
             WHEN value = 'T' THEN [Date]
           END) Tdate
FROM   (SELECT Row_number()
                 OVER (
                   partition BY id,value
                   ORDER BY date)%@cnt rn,*
        FROM   #test) a
GROUP  BY id,rn

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