IF EXISTS (SELECT 1 FROM SYSOBJECTS WHERE name = 'tb')
BEGIN
    DROP TABLE tb
END
GO
create table tb(col1 int,col2 int,col3 varchar(10))
insert into tb
 select 1,1,'a' union
select 1,2,'b' union
select 2,4,'c' 

select a.col1,b.number,a.col3
from tb a,master..spt_values b 
where a.col2 <= b.number and number < (select MIN(col2) from tb where col3 > a.col3) and b.type='p'
UNION
select a.col1,b.number,a.col3
from (SELECT rn=ROW_NUMBER() OVER (PARTITION BY col1 ORDER BY col2),col1,col2,col3 FROM tb) a,master..spt_values b 
where b.type='p' AND rn = 1 AND number <= col2 AND number > 0

col1    number    col3
1    1    a
1    2    b
1    3    b
2    1    c
2    2    c
2    3    c
2    4    c

------解决方案--------------------

引用http://topic.csdn.net/u/20120614/16/adb230c1-205e-41cb-9356-744d07ccef5f.html#r_78865191
SQL code
--完整如下:
if object_id('[tb]') is not null drop table [tb]
go 
create table [tb]([line] int,[count] int,[serial] int)
insert [tb]
select 1,2,22 union all
select 1,3,23 union all
select 2,7,24

--------------开始查询--------------------------
select line,row_number()over(partition by line order by line),serial
from
[tb] a
left join
master..spt_values c
on
   c.number<=a.[count]
and
   c.number>0
and
   c.[type]='p'