Cumulative output based on flag...

Question

Hi,
I have a table as
Txn No Flag Amt
1 C 500
2 D 100
3 C 200
4 C 100
5 D 400
6 D 100
I am trying to write a query which will give me the total amount that is based on the Flag value i.e. D or C.
If Flag is D subtract the current amount from previous amt
if Flag is C add the current amount to previous amt
Txn No Flag Total Amt
1 C 500
2 D 400
3 C 600
4 C 700
5 D 300
6 D 200
Please guide me...
Thanks in advance
Regards
Kaustubh

Answer 1

Like this ?
SQL> with tbl as
  2  (select 1 as c1, 'C' as c2, 500 as c3 from dual union all
  3   select 2, 'D', 400 from dual union all
  4   select 3, 'C', 600 from dual union all
  5   select 4, 'C', 700 from dual union all
  6   select 5, 'D', 300 from dual union all
  7   select 6, 'D', 200 from dual )
  8  select c1,c2, c3, sum(decode(c2,'C',c3,c3*-1)) over (order by c1)
  9  from tbl;
        C1 C         C3 SUM(DECODE(C2,'C',C3,C3*-1))OVER(ORDERBYC1)
         1 C        500                                         500
         2 D        400                                         100
         3 C        600                                         700
         4 C        700                                        1400
         5 D        300                                        1100
         6 D        200                                         900
6 rows selected.
SQL> Nicolas.