关于自表更新的问题

[律己修心]

有这样一个表
I S E
5 2008/02/02 2008/05/02
5 2008/03/02 2008/05/02
5 2008/04/02 null

现想要更新这个表
在I值相同的条件下
用E值段来更新S值段

更新后的结果应该是这样的
I S E
5 2008/02/02 2008/03/02
5 2008/03/02 2008/04/02
5 2008/04/02 null

S值段值最大的不被更新

请问应该怎样实现？
谢谢

[青锋-SS]

update tb
set e=(select min(s) from tb a where a.i=tb.i and a.s>tb.s)

[青锋-SS]

create table tb(I int,S datetime,E datetime)
go
insert into tb select 5,   '2008/02/02',   '2008/05/02'
insert into tb select 5,   '2008/03/02',   '2008/05/02'
insert into tb select 5,   '2008/04/02',   null 
go
select i,convert(char(10),s,120) as s,convert(char(10),e,120) as e from tb
update tb
set e=(select min(s) from tb a where a.i=tb.i and a.s>tb.s)
select i,convert(char(10),s,120) as s,convert(char(10),e,120) as e from tb
go
drop table tb
go



i           s          e
----------- ---------- ----------
5           2008-02-02 2008-05-02
5           2008-03-02 2008-05-02
5           2008-04-02 NULL

(3 行受影响)

(3 行受影响)

i           s          e
----------- ---------- ----------
5           2008-02-02 2008-03-02
5           2008-03-02 2008-04-02
5           2008-04-02 NULL

(3 行受影响)