Stored Procedure to create cumulative sums - sql

Question

I'm trying to write Firebird stored procedure, which returns me cumulative sums for twelve months grouped by another two fields.
For now I created something like this:
SET TERM ^ ;
CREATE PROCEDURE A_OBRATZISKKUM(
START_YEAR INTEGER,
END_YEAR INTEGER)
RETURNS(
OBRAT DOUBLE PRECISION,
MESIC INTEGER,
ROK INTEGER,
SECURITYUSER_ID TYPE OF ID COLLATE WIN1250,
FIRM_ID TYPE OF ID COLLATE WIN1250)
AS
DECLARE VARIABLE act_month INTEGER = 1;
begin
for select
sum(AO.Obrat), :act_MONTH, :start_YEAR, AO.SecurityUser_ID,
AO.Firm_ID
from A_OBRATYKUMHIST_TEMP AO
where
AO.Rok = :start_year
and AO.Mesic <= :act_month
group by
AO.SecurityUser_ID, AO.Firm_ID
into :obrat, :mesic, :rok, :securityuser_id, :firm_id
do
act_month = :act_MONTH + 1;
suspend;
end^
SET TERM ; ^
But when I run it I get only one row with weird sum. What's wrong on my code?
EDIT1.
I come out from this sql query:
select
sum(AO.Obrat), *1*, 2012, AO.SecurityUser_ID,
AO.Firm_ID
from A_OBRATYKUMHIST_TEMP AO
where
AO.Rok = 2012
and AO.Mesic <= *1*
group by
AO.SecurityUser_ID, AO.Firm_ID
When I take for example month number 3, I get sum of all previous months grouped by securityuser_id and firm_id.
But if I want to get sums for all months, then I have to run this twelve times with replacing 1 for 2, then for 3, then ........
At the end I get cumulative sums splits up to months, years, users and firms.

Answer 1

A DO is followed by either a single statement, or by a block. You are currently doing a single SUSPEND instead of multiple suspends as your intention is. Instead of
FOR SELECT ...
DO
statement;
SUSPEND;
You need to do
FOR SELECT ...
DO
BEGIN
statement;
SUSPEND;
END
Also the statement act_month = :act_MONTH + 1; should be act_month = act_MONTH + 1; (no colon :)
The running sum
The running sum can be achieved by self-joining for all months <= the current month and summing over that:
SELECT SUM(AO2.Obrat), AO.Mesic, AO.Rok, AO.SecurityUser_ID, AO.Firm_ID
FROM A_OBRATYKUMHIST_TEMP AO
INNER JOIN A_OBRATYKUMHIST_TEMP AO2
ON AO2.Rok = AO.Rok AND AO2.Mesic <= AO.Mesic
WHERE AO.Rok = 2012
GROUP BY AO.Mesic, AO.Rok, AO.SecurityUser_ID, AO.Firm_ID
Note this only works within the same year, you'd need to modify the join condition if you need to sum over multiple years.