select a , b, c, row_number() over(partition by a , b, c order by a , b, c) rw from tb

------解决方案--------------------
SQL code
create table tb(a int,b int,c int)

insert into tb values(1,1,2)

insert into tb values(1,1,2)

insert into tb values(1,2,3)

insert into tb values(2,2,2)


select a , b, c, row_number() over(partition by a , b, c order by a , b, c) rw from tb

/*
                                      A                                       B                                       C         RW
--------------------------------------- --------------------------------------- --------------------------------------- ----------
                                      1                                       1                                       2          1
                                      1                                       1                                       2          2
                                      1                                       2                                       3          1
                                      2                                       2                                       2          1
4 rows selected
*/

drop table tb

------解决方案--------------------
楼上正解！

------解决方案--------------------
SQL code

--晕，没看到你最后一句话要按a,b,c分组
row_number()over(partition by a,b,c order by a,b,c)

------解决方案--------------------
探讨

SQL code
select a , b, c, row_number() over(partition by a , b, c order by a , b, c) rw from tb


------解决方案--------------------
partition by下就可以了

------解决方案--------------------
探讨

数据
a|b|c
-----
1|1|2
1|1|2
1|2|3
2|2|2

希望取出格式如下

a|b|c|rw
---------
1|1|2|1
1|1|2|2
1|2|3|1
2|2|2|1

===============
用row_number按a分组能得出以下结果

a|b|c|rw
---------
1|1|2|1
1|1|2|2
……