Question on Decode function.

Question

I have the following table structure.
Table name: TMP_tab_1
Columns: role_id
: comm_code
: amount
I need to write a sql statement for
If role_id = 280 and comm_code <> 330 then
sum(amount)
end if
Please advise how to use decode to resolve the above issue.
Thanks.

Answer 1

Why decode?
select sum(amount) from TMP_tab_1 where role_id=280 and comm_code<>330;
Above returns the amount summed for all rows.
If you have non-distinct role/comm and you want amounts summed at that level
select role_id, comm_code, sum(amount)
from TMP_tab_1
where role_id=280 and comm_code<>330
group by role_id, comm_code;
If you need to see everybody but suppress amount for many, then
select role_id, comm_code, sum(decode(role_id, 280,decode(comm_code, 330,0, amount), 0))
from TMP_tab_1
group by role_id, comm_code;