Time calculation

[anlimah]

I am trying to calculate two time fields and automatically populate my length field e.g. start: 9:00AM end: 10:00am the answer is obviously 1:00 hour. However, I am confused about how to have the result automatically displayed in my length field after the calculation. Not sure as to how I would datediff() I am new to this function, so please bear with me. What would the expression look like and where should it be placed. Should the expression be placed in the after update property on my end field? Thanks.

[June7]

Saving calculated data is usually ill-advised and requires code. Just do the calculation in query when needed.