Calculating Sum of Duration From Multiple Time Stamps

Srinath,

I would suggest an architecture change so that you can capture the Duration from a Child Table and then Summarize that Duration in the Parent Table.

Here is a small ERD to show what I am proposing

The [Duration] in the Child table would be a Formula Duration  [Stop]-[Start] where both are Date/Time fields.

You then use a Summary field in the Relationship between Parent and Child to add together all the Durations from the Child table.

As a work flow issue you will need to make sure that Users can only add a Child and set [Start] when the last Child record has a value for [Stop].  You can do this by creating another value in the Relationship called Max RID Child.

Here is a screen shot of the creation process

Now you know which Child record holds the most current Start and Stop.   There are a variety ways to control the Users ability to create child records and edit them.  My personal favorite is to use Formula Rich Text field where you evaluate the Child Record.  You can also set the ability to modify the records based upon the value of [Stop]

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Don Larson
Paasporter
Westlake OH
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