BEFORE INSERT trigger with stored procedure call (DB2 LUW 9.5) - stored-procedures

Question

I am trying to create a BEFORE INSERT trigger that will check the incoming value of a field, and replace it with the same field in another row if that the field is null. However, when I add the CALL statement to my trigger, an error is returned "The trigger "ORGSTRUCT.CSTCNTR_IN" is defined with an unsupported triggered SQL statement". I checked the documentation and saw that cursors weren't supported in the BEFORE (part of the reason for making the stored procedure in the first place), but even when I remove the cursor declaration from the stored procedure the call still generates the same error.
Trigger:
CREATE TRIGGER orgstruct.cstcntr_IN
NO CASCADE
BEFORE INSERT ON orgstruct.tOrgs
REFERENCING NEW AS r
FOR EACH ROW MODE DB2SQL
BEGIN ATOMIC
DECLARE prnt_temp BIGINT;
DECLARE cstcntr_temp CHAR(11);
SET prnt_temp = r.prnt;
SET cstcntr_temp = r.cstcntr;
CALL orgstruct.trspGetPrntCstCntr(prnt_temp,cstcntr_temp);
SET r.cstcntr = cstcntr_temp;
END
Stored procedure:
CREATE PROCEDURE orgstruct.trspGetPrntCstCntr (
IN p_prnt BIGINT,
OUT p_cstcntr CHAR(11)
)
SPECIFIC trGetPrntCstCntr
BEGIN
IF p_prnt IS NULL THEN
RETURN;
END IF;
BEGIN
DECLARE c1 CURSOR
FOR
SELECT cstcntr
FROM orgstruct.tOrgs
WHERE id = p_prnt
FOR READ ONLY;
OPEN c1;
FETCH FROM c1 INTO p_cstcntr;
CLOSE c1;
END;
END
According to the documentation, CALL is allowed in a BEFORE trigger, so I don't understand what the problem is.

Answer 1

A before trigger can call a stored procedure, but the stored proc can't do anything not allowed in the trigger.
In your case, the default level of data access for a SQL stored proc is MODIFIES SQL DATA, which is not allowed in the trigger. You could recreate your stored procedure, changing the data access level to READS SQL DATA; this will allow you to create the trigger.
However: There is no reason to call a stored procedure for something this simple; You can do it using a simple inline trigger:
create trigger orgstruct.cstcntr_IN
no cascade
before insert on orgstruct.tOrgs
referencing new as r
for each row
mode db2sql
set r.cstcntr = case
when r.p_prnt is not null
then (select cstcntr from tOrgs where id = r.p_prnt fetch first 1 row only)
else r.cstcntr
end;
This will be a LOT more efficient because it eliminates both the stored procedure call and the cursor processing inside the stored proc. Even if you wanted to use the stored proc, you could eliminate the cursor inside the stored proc and improve performance.
FYI: the logic that you posted contains an error, and will always set CSTCNTR to NULL. The trigger posted in this answer not do this. :-)