Stored Procedure to create cumulative sums

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.