--> 测试数据：[tb]
if object_id('[tb]') is not null drop table [tb]
go 
create table [tb]([ID] int,[列] varchar(1),[内容] int)
insert [tb]
select 1,'A',100 union all
select 2,'A',200 union all
select 3,'C',300 union all
select 4,'B',300 union all
select 5,'A',300 union all
select 6,'C',200
--------------开始查询--------------------------
--2005/2008
select *,序号=row_number() over(partition by [列] order by id) from [tb]
--2000
select *,序号=(select count(1) from tb where [列]=t.[列] and id<=t.id) from [tb] t order by 列,序号
----------------结果----------------------------
/* 
ID          列    内容          序号
----------- ---- ----------- --------------------
1           A    100         1
2           A    200         2
5           A    300         3
4           B    300         1
3           C    300         1
6           C    200         2

(6 行受影响)
*/

------解决方案--------------------
SQL code
select *,序号=row_number() over(partition by 列 order by 内容)
from tb