Yes I do! I also had to speed up the process of calculating a field each time an update was made to the table (in my case inventory availability field) so the user could check it in real time and a trigger saved my life :)

Only difference is I use them in a SQL Server backend but as I said in a previous post to Cetin the general concept must be the same.

>Thanks Enmanuel, I guess that means you prefer doing the calculation each time an update is made and storing the balance. (BTW I know what a trigger is and have used them many times <s>.)
>
>>You can have a trigger that calculates the oustanding balance everytime a receipt is entered.
>>
>>Check for triggers on the help!
>>
>>>Hi,
>>>
>>>I couldn't find a section for design questions like this, so I've placed it here in chatter.
>>>
>>>I am working on a system where sales are entered, then when payments are received a receipt gets printed. The receipt and the invoice both show the balance due or outstanding.
>>>
>>>The tables I have are Sales and Sale Details and Payments and Payment Details.
>>>
>>>The Sales table has a field for Balance Due and the Payment Details table (related to the Sales table by Sale ID) also has the balance due stored in it.
>>>
>>>I have two problems with this design:
>>>
>>>1. Editing Payments causes problems with the balance due. For example, I make a sale for $600, then a payment of $400 is made against this sale. The Balance due on the Sale is put to $200 and the Balance Due on the Payments details record for this sale is put at $200. If another payment gets made of say $100, then the Sale's balance due is set to $100 and the payment details is set to $100. If I realise that a mistake was made on the first payment and it was actually $250 that should have been entered, changing the $200 payment to $250 causes all my balances to go off.
>>>
>>>Should I not let a payment be changed? Only let them add new payments?
>>>
>>>Or would a re-design help? Any suggestions?
>>>
>>>Or is the design good enough and it is just that I need to change the way my calculations are done when calculating the balance due?
>>>
>>>2. I dislike having calculated fields stored in the tables, I would much prefer to calculate the balance due on the fly. However doing it this way speeds up reporting and the user interface, so I will live with this.
>>>
>>>Thanks for any opinions.