How to calculate the total of expenses?
I have problem when I try to calculate the total of expenses. I got 2 table as below;
expenses(po_no, po_amount, po_cancel, total_expenses)
Let say :
user1 - po_amount is $200
user2 - po_amount is $300
I want total_expenses = $500
So, what is the formula that i can use to calculate. I have try to use global variable, but when I try to deduct amount from po_cancel, the amount of total_expenses is still same, unchange.