Calculta values from different tables.

[Marcus]

Hi.
I have a litle problem.
I have two tables, this fields are included in the first:
Startnr, Starttime and in the second table: Startnr,
finishtime. I have a relation between startnumbers but my
problem is that each startnumber have more than one start
and finishtime and I want to calculate the diferense
betwen the times. I only want the result of first
finishtime-first starttime then second finishtime-second
starttime and so on....

How to do?

 

[Marcus]

I forget one thing! In each table I have a Indexfield,
each time have a different index but it´s not shore that
both times have the same indexvalue. But the finishtime
always have a higer value than the starttime.