ovid's point is valid, but if you had some compelling need for a running total ... perhaps a great many relatively small transactions that would make re-computing the total more time consuming that you want the app to handle, you could always create another table to hold the totals ... that wouldn't have to violate normalization rules. if your database server has enough muscle, you could use a stored procedure to do the total when a change had been made. postgresql has perl stored procedure scripting support, so you could even keep it in the family.