请问怎么用update更新数据表里的最后一条记录？

[mailto520]

表名：abc

id username outdate
1 admin 2008-08-10
2 admin 2008-08-12
3 admin 2008-10-15

现在我要将最后一条记录(id=3)的记录的outdate更新为今天,现在我不知道ID。
如果我用 update abc set outdate=getdate() where username=admin 多条记录都更新了，请问怎么才能只更新最后一条记录

[hsie168518]

update   abc   set   outdate=getdate()   where   username=admin   and id=3

[yiyi_wx]

update abc set outdate=getdate() where id=(select max(id) from abc)

[mailto520]

自己搞出来了
update abc set outdate=getdate() where id=(select top 1 id from abc where username='admin' order by id desc)

[Andy-W]

update abc set outdate=getdate() where id=(select max(id) from abc)

[ChinaJiaBing]

declare @abc table(id int,username varchar(10),outdate datetime)
insert into @abc select 1,'admin','2008-08-10'
       union all select 2,'admin','2008-08-12'
       union all select 3,'admin','2008-08-15'
update a set a.outdate=getdate() from @abc a join (select top 1 * from @abc order by id desc)b
             on a.id=b.id
select * from @abc

1	admin	2008-08-10 00:00:00.000
2	admin	2008-08-12 00:00:00.000
3	admin	2008-11-01 11:28:34.920

[njtimenowht]

update abc
set outdate=getdate()
where id=(select max(id) from abc)

username='admin' 可以不写。

另外主要日期格式