how to get previous row value for a column

I am trying to create a bank balance database to keep track of the money going in and out of a bank account, but I can't seem to set up a computerized balance column to automatically add the money going in and subtract the money going out to/from the previous rows balance cell.

Can anyone PLEASE help?

[316 byte] By [sugarplum] at [2007-12-23]
# 1
The data column allows you to use an expression. Unfortunately it does not support anything this complex. I think you will manually keep track of the running total.
KenTucker at 2007-8-31 > top of Msdn Tech,Windows Forms,Windows Forms Data Controls and Databinding...