Computing sums

Question

Does any1 know how to compute sums and averages from a master block into a detail block using PL/SQL triggers?
Thanks for your help.

Answer 1

Hi,
If you have Forms later than 5.0, you have the possibility to have summary fields.
Using triggers is a bit tricky, yet here's how to do.
Make a package spec program unit, named, say vars, where you may have variables visible throughout all form code. So, there you'll have declared:
old_numval number;
(used to store the value of an item used for calculating the sum prior to the item modification).
In the when-new-item-instance of the item used to calculate the sum you'll have:
vars.old_numval:=nvl(:your_block.your_summarised_item, 0);
In the when-validate-item for the summarised item:
:your_summary_block.x_summary_item:=:your_summary_block.x_summary_item-vars.old_numval+nvl(:your_block.your_summarised_item, 0);
I use nvl due to the fact that if you have null items those would give a null sum.
This is how to calculate a sum field. An average field would be almost the same thing.
One matter is that you'll usually have to have all the querried records fetched (which might be a problem if there are many records).
Best of luck,
BD.