求一个sql语句

[yishanjushi]

请到下面的网子帮我看一下。谢谢
http://expert.csdn.net/Expert/topic/2669/2669664.xml?temp=.9270441

[xieyj]

select distinct username,max(createtime) from tablename group by username order by createtime

[say1no2]

select distinct xinghao,max(dd) from product group by xinghao

group子句不能加order by

[say1no2]

错了，最多只能这样
select distinct xinghao,max(dd) from product group by xinghao order by xinghao desc

[say1no2]

如果指定了 SELECT DISTINCT，那么 ORDER BY 子句中的项就必须出现在选择列表中。


select distinct xinghao,max(dd) as dtime from product group by xinghao order by dtime asc

[loveweb]

回复人： zjcxc(邹建) ( ) 信誉：216 2004-01-16 14:19:00 得分:0
select distinct * from 表 a
where createtime=(select max(createtime) from 表 where username=a.username)
order by createtime
--用distinct 是为了保证,如果createtime要相同,只取一个.如果没有这个问题,不需要distinct
--说明,如果你的表中就这两个字段,大家的方法都可以.

如果你的表中还有其他字段,并且这些字段都要显示出来,就要用我的方法
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这个好