Subject Running total column
Author Eyal

I use the TIBO* components with 3rd party DB aware controls. I need to
display accounting data in a grid, which is more or less trivial except...

I need to display a column of the running total - that is, for each
row the running total = (running total of previous row) + current row.
For example:

# Date Desc. Amount RunTot
1 1/1 Blah 100 100
2 2/2 Ding 200 300
3 3/3 Dong 300 600
4 4/4 Oops -400 200

The problem is that I can't use a calculated column, because for each
row the calculation event will need to access data from all previous
rows. This results in the current row changing during the event (which
wreaks havoc on connected controls), and very slow when there are
several hundred rows.

Another possible solution is to include a dummy column in the query,
which creates another column, and then calculate the running totals
once and store them in that column. However this marks all the rows
for update, altough nothing really has changed in the underlying DB data.

What I need is a "virtual column" that I can populate with the values
I want, without disturbing the update status of the rows.

Is there any such thing?