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DISTINCT Stock, A, B, C, D, E
是这条记录DISTINCT,而不是当中的某些都不同,请正确了解DISTINCT,谢谢。
最好给出完整的表结构,测试数据,计算方法和正确结果.
参考
下面是以ForumID 分组
去时间最大的
if not object_id('tp') is null
drop table tp
create table tp
(
TopicID int,
ForumID int,
LastReplier varchar(10),
LastReplyTime datetime
)
insert into tp select 1,1,'A1','2010-09-16 16:32:37.347'
union all select 2,1,'A2','2010-09-15 16:47:40.750'
union all select 3,1,'A3','2010-09-17 15:29:41.983'
union all select 4,2,'A1','2010-09-13 12:19:21.983'
union all select 5,2,'A3','2010-09-13 13:20:34.750'
select * from tp b where not exists
(select * from tp where ForumID=b.ForumID and LastReplyTime>b.LastReplyTime)
TopicID ForumID LastReplier LastReplyTime
----------- ----------- ----------- -----------------------
3 1 A3 2010-09-17 15:29:41.983
5 2 A3 2010-09-13 13:20:34.750
(2 行受影响)