I have 3 time fields: Time_Start, Time_Finish and Time_Duration.

I want to be able to:

1. Automatically return the difference between Time_Start and Time_Finish into Time_Duration.

2. The sum of Time_Duration.

Please, can anybody tell me the best way of doing this? Should Time_Duration be a Calculated Field giving a time result or a Time Field with an auto enter calculation? What is the difference between the 2 ways of doing it?

Many thanks in advance.

Time_Duration should be a calculation field (result is Time)=

Time_Finish - Time_Start

This needs some adjustment if it's possible to finish after midnight.

You can sum time fields (or calculation fiels set to result of Time) the same way as number fields. Time is just a number (the number of seconds elapsed since midnight).

Use auto-enter calculation when:

- you want the user to be able to override the result, or

- the calculation itself cannot be stored, and you need the field to be indexed.

Edited November 10, 200520 yr by Guest

:thumbup: Many thanks, I'll try that.