急！！！！如何批量的给表内记录中某个字段递增编号
如表
id       name
----------
2         ee
2         rr
7         xx
9         ss
17       ww


现在要变成
id       name
----------
1         ee
2         rr
3         xx
4         ss
5         ww

请问这个update该怎么写啊？

------解决方案--------------------
create table t(
id int,
name varchar(10)
)
insert into t
select 2, 'ee '
union all select 2, 'rr '
union all select 7, 'xx '
union all select 9, 'ss '
union all select 17, 'ww '

select identity(int,1,1) as [id],[name] into #t from t

select * from #t

update t set id=a.id from #t a where a.name=t.name
select * from t
drop table #t
drop table t
------解决方案--------------------
alter table t1 with nocheck add sn int identity(1,1);
update t1 set id=sn;
alter table t1 drop column sn;

------解决方案--------------------
update tab set tab.id = tt.id2
from
(
select id2 = (select count(1) from tab where id < a.id or (id = a.id and name = a.name)),id,name
from tab a
)tt
where tab.id = tt.id and tab.name = tt.name