Calculate Serial number Invoice ID

[jschone]

Dear all,

I have a table with a field that can have the status:

-Quotes

-Orders

-Invoice

What I am trying to achieve is, if that if the status is Invoice it has to use the next number in line. So let's say the last invoice was 55, it becomes 55 + 1.

I all order cases (quotes, orders) the Invoice ID field has to remain empty.

I've tried many ways, but I don't how to make the calculation from the last record with a populated Invoice ID field +1.

Kind Regards, Jochem

Edited July 15, 2009 by Guest