Enumerate (count) records in groups

[DemBones79]

I have a table that stores (among other things) district number and order number. Each order can have multiple transaction dates (each time it has been touched). What I need is a SELECT statement that can give me an ascending sequence for each record grouped by district and order.

So if the columns are: district, order, tr_date

And the data might look like this:
0021, 00001111, 01/12/09
0021, 00001111, 01/15/09
0021, 00001111, 01/23/09
0021, 00001213, 01/14/09
0021, 00001213, 01/16/09
0018, 00001019, 12/27/09

Would need to look like this:
0021, 00001111, 01/12/09, 1
0021, 00001111, 01/15/09, 2
0021, 00001111, 01/23/09, 3
0021, 00001213, 01/14/09, 1
0021, 00001213, 01/16/09, 2
0018, 00001019, 12/27/09, 1

Any ideas?

 

[DemBones79]

I think I figured it out:

select
     t1.district,
     t1.order_no,
     t1.tr_date,
     sum(case when t2.tr_date <= t1.tr_date then 1 else 0 end) as tr_seq
from
     tbl_example t1
     inner join
     (select
          district,
          order_no,
          tr_date
     from
          tbl_example) t2
          on
          t1.district = t2.district
          and
          t1.order_no = t2.order_no
group by
     t1.district,
     t1.order_no,
     t1.tr_date

It seems to work, at least.