求一条sql语句~~
ID   PostID      UserID 
 1         1000            100 
 2         1000            100    
 3         1000            1001 
 4         1001            100 
 ---------------------------- 
 怎么取出UserID=100的POSTID不一样的数据。 
 也就是得出的结果应该是 
 4         1001            100 
 2         1000            100
------解决方案--------------------select max(id),postid,id from tab group by postid,id      
 ***************************************************************************** 
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 http://www.cnblogs.com/feiyun0112/archive/2006/09/20/509783.html
------解决方案--------------------  select * from T as tmp 
 where tmp.UserID= '100 ' and 
 (select count(*) from T where UserID= '100 ' and PostID=tmp.PostID)=1
------解决方案----------------------這樣?     
 create table T(ID int, PostID varchar(10), UserID varchar(10)) 
 insert T select   1,    '1000 ',     '100 ' 
 union all select 2,    '1000 ',     '100 ' 
 union all select 3,    '1000 ' ,    '1001 ' 
 union all select 4,    '1001 ' ,    '100 '   
 select ID=max(ID),PostID,UserID= '100 ' 
 from T as tmp 
 where tmp.UserID= '100 ' 
 group by PostID   
 --result 
 ID          PostID     UserID  
 ----------- ---------- ------  
 2           1000       100 
 4           1001       100   
 (2 row(s) affected) 
------解决方案--------------------select max(id),postid,UserID  
 from tab  
 where UserID=100 
 group by postid,UserID 
------解决方案--------------------select max(id),PostID,UserID from tbmp 
 where UserID=100 group by PostID,UserID
------解决方案--------------------借用ls的环境:) 
 create table T(ID int, PostID varchar(10), UserID varchar(10)) 
 insert T select   1,    '1000 ',     '100 ' 
 union all select 2,    '1000 ',     '100 ' 
 union all select 3,    '1000 ' ,    '1001 ' 
 union all select 4,    '1001 ' ,    '100 '     
 select max(id) ID,postid,UserID  
 from T  
 where UserID=100 
 group by postid,UserID     
 ------------------------ 
 ID  postid UserID    
 2	1000	100 
 4	1001	100