Display '0s' for null database items Please help!

Question

Hi all,
I need your help on a possible minor problem I'm encountering. I have 5 fields (all numeric data types) on my form of which, the last field is a sum (formula non-database item) of the top four items. 2 out of the remaining 4 fields are database text items in which I'd like to update the database based on user input. The table that stores the 4 values does not require data and defaults to null if no data present.
What I'd like to do is display a '0' on the form so that its visible and it could get added to the formula sum item but not update the database fields with a '0' (if any one of those top 4 fields returns null from the table ). I've tried creating a formula in the property palette on the fields with an nvl(field,0) function and got a chain reference error that I couldn't figure out based on the oracle error suggestions. Does anyone have any suggestions on how I could handle my request. Any help would be greatly appreciated.
Thanks,
Eric

Answer 1

Zakiy,
I don't know much about the POST-CHANGE trigger. Did a little research and posted some code in there retrieving the nvl(field) value. It compiled ok but didn't display the '0.' I'm not sure if I used the trigger the right way.
Here's my code:
DECLARE
v_points NUMBER;
CURSOR c_points IS
(SELECT nvl(points,0)
FROM student
WHERE student_id = :id);
BEGIN
OPEN c_points;
FETCH c_points INTO v_points;
CLOSE c_points;
END;
If this is incorrect, do you have an example from what you were thinking? Also, just out of curiosity, why do you recommend this trigger over the formula?
From what I was mentioning before, I don't know why the formula w/the nvl works in the sum field but doesn't in the other 4 fields. The sum field is a non-database item whereas 2 others are display items and the remaining 2 are text items. Seems simple enough to use the nvl in the formula section for all 4 fields I kept getting that error.
Eric