How to calculate value with UPDATE current record

[Roger Desmedt]

Hi,

I have a table with 4 fields; id (key), start, stop, total
It gets the data from another table by trigger (start, stop and total).

How can I re-calculate the field "total" when I change start or stop by hand (UPDATE)?
I don't want to use FOR EACH ROW since it will re-calculate the whole table.

Is there a way to retrieve the id of the particular record so I can use it with WHERE or is there another way?

KR,
Roger