Running Total in a Billing Portal
I've been trying to figure this out for a couple of months now and I'm completely befuddled. I even tried posting this same question on here a while back but couldn't get an answer that made sense to me.
--I have two tables: Client and Billing
--I have a portal in Client showing each bill, sorted by creation date in descending order
--There is a field called Current Charge (which is, you guessed it, the current bill amount), a field called Balance Due Calc (the one I need help with, reflecting the existing Balance Due from the previous bill) and a field called Balance Due Total (which is a calculation Balance Due Calc + Current Charge).
I need to figure out how to have a calculation for Balance Due Calc that will somehow show the Balance Due Total from the previous bill, and to have that a dynamic calc (for example, someone forgot to put in a payment for that week until after the next bill had been generated, went back and put in the payment for that bill, and then all of the subsequent bills will reflect the changed status).
I'm using Filemaker 9 to design with, on a Mac, if that makes any difference.
Thanks so much to anyone who can explain this to me. I really feel like a dunce for not being able to figure this one out...<!-- StartFragment --><!-- EndFragment -->