>>>>Are you saying that I should store the current and past balances in every
>>>>detail record? That's something I hadn't thought of. (Mulling over the
>>>>possibilities...)
>>>Stop mulling right now before you do permanent damage. :-) The answer is no!
>>Why? That's the best solution I've seen so far.
>
>Because if you delete a detail line somewhere, you have to recompute all the balances after it, for example....

I've dealt with this issue before in accounting/financial applications. It's also a major concern in OLAP apps and data-warehousing. The simplist way that I have found to address it is to create a summary table of running balances per month, quarter, year. Every single entry updates (or creates and updates) the summary table entry applicable. In my situation, I was trying to avoid doing million-record SUMs for simple P/L reporting.