Generate Sequence Number based on other columns

Hi,
Please help me to find a solution.

My requirement is similar to this.
Example:

TABLEA(pk_id, pol_mas_id,pol_seq_id)

values are
pk_id pol_mas_id pol_seq_id
1 1
2 1
3 2
4 2
5 3
6 3
7 3

Now i need to update the column "pol_seq_id" as below.

pk_id pol_mas_id pol_seq_id
1 1 1
2 1 2
3 2 1
4 2 2
5 3 1
6 3 2
7 3 3

Currently i am using cursor and you know performance sucks.

Is there any way to increment the data in the column(pol_seq_id) based on other column (pol_mas_id).

Thanks in Advance!!

Try:

select

pk_id, pol_mas_id, row_number() over(partition by pol_mas_id order by pk_id) as pol_seq_id

from

dbo.t1

go

It is helpful to have an index by (pol_mas_id, pk_id)

AMB

|||Thanks a lot for the response !!!
It works for select as when i am trying to update the same i am getting this error
"Windowed functions can only appear in the SELECT or ORDER BY clauses."
so i have populated the same into #temp table and then updated with join statement.

It works
|||

Try using a CTE.

;with cte

as

(

select

pk_id, pol_mas_id, pol_seq_id, row_number() over(partition by pol_mas_id order by pk_id) as rn

from

dbo.t1

go

)

update cte

set pol_seq_id = rn;

AMB