time calculations

[martie]

I have this problem in two different Dbs now. I have a simple time calculation - finish time - start time. How can I make it NOT calculate until both fields are entered? Currently, I get some huge figure as a result when there is no data in the finish time field. If I add a check on the finish field (IsEmpty or IsValid or <=0, I get 00:00:00.

What I want is for the calculation not to happen until there is a valid finish time entered. Is this possible?

Thank you!

Martie

[-Queue-]

Case( Length( finish time ), finish time - start time )

[martie]

how clever, how simple, how lovely!

thank you!

Martie