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
[解决办法]
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
[解决办法]
select * from T as tmp
where tmp.UserID= '100 ' and
(select count(*) from T where UserID= '100 ' and PostID=tmp.PostID)=1
[解决办法]
--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)
[解决办法]
select max(id),postid,UserID
from tab
where UserID=100
group by postid,UserID
[解决办法]
select max(id),PostID,UserID from tbmp
where UserID=100 group by PostID,UserID
[解决办法]
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
21000100
41001100
