请教查找记录的问题！

[NTM2008]

'a' '20100501'
'a' '20100502'
'a' '20100503'
'b' '20100401'
'b' '20100402'
'b' '20100403'
需要按照时间倒序找出以上着颜色的记录。

[bill024]

select * from tb t where not exists(select 1 from tb where name=t.name and date>t.date)

[caixia615]

select col1,max(col2)col2 from table group by col1