这个列转行该怎么实现

这个列转行该如何实现？
表

SQL code

Create table ttt(ID int not null,SID int ,A varchar(10))INsert into tttSelect 1,1,'aa'UnionSelect 1,2,'bb'unionSelect 1,3,'cc'UnionSelect 2,1,'a'UnionSelect 2,2,'B'Select ID,Case when sid=1 then A else Null End as sid1,Case When Sid=2 then A else Null End as sid2,Case When Sid=3 then A Else Null End as Sid3 From ttt group by id,A,Sid

SQL code

ID,Sid1,Sid2,Sid31, aa,   bb,  cc2, a,    B---进行到上面一步查询不会了 

SQL code

Select ID,max(Case when SID=1 then A else Null End) SID1 ,max(Case when SID=2 then A else Null End) SID2 ,max(Case when SID=3 then A else Null End) SID3From ttt group by ID
[解决办法]
SQL code
Create table ttt(ID int not null,[SID] int ,A varchar(10))INsert into tttSelect 1,1,'aa'UnionSelect 1,2,'bb'unionSelect 1,3,'cc'UnionSelect 2,1,'a'UnionSelect 2,2,'B'--[SID]字段值较多时推荐使用动态转换declare @str varchar(1000)set @str=''select     @str=@str+',['+ltrim([SID])+']=max(case when [SID]='    +LTRIM([SID])+' then A else '''' end)'from     tttgroup by     [SID]exec('select ID'+@str+' from ttt group by ID')/*ID    1    2    3-----------------1    aa    bb    cc2    a    B    */
[解决办法]
SQL code
Create table ttt(ID int not null,[SID] int ,A varchar(10))INsert into tttSelect 1,1,'aa'UnionSelect 1,2,'bb'unionSelect 1,3,'cc'UnionSelect 2,1,'a'UnionSelect 2,2,'B'--[SID]字段值较多时推荐使用动态转换declare @str varchar(1000)set @str=''select     @str=@str+',[SID'+ltrim([SID])+']=max(case when [SID]='    +LTRIM([SID])+' then A else '''' end)'from     tttgroup by     [SID]exec('select ID'+@str+' from ttt group by ID')/*ID    SID1    SID2    SID3------------------------------1    aa    bb    cc2    a    B        */
[解决办法]
SQL code
Create table ttt(ID int not null,SID int ,A varchar(10))INsert into tttSelect 1,1,'aa'UnionSelect 1,2,'bb'unionSelect 1,3,'cc'UnionSelect 2,1,'a'UnionSelect 2,2,'B'select ID,       isnull([1],'') Sid1,       isnull([2],'') Sid2,       isnull([3],'') Sid3from ttt apivot(max(A) for SID in([1],[2],[3])) p/*ID          Sid1       Sid2       Sid3----------- ---------- ---------- ----------1           aa         bb         cc2           a          B          (2 row(s) affected)*/