How To Add A New Column With Custom Date Field

Summary:

I have an OTBI report where I need to add a column (see expected date column below) that when there is a Termination Date it shows the Termination Date BUT when there is no Termination Date it shows the Work Relationship Start Date. I tried creating a CASE statement for when Termination Date is null, show Work Relationship Start Date, else show Termination Date but was not successful. I would appreciate some guidance on how to do this please.

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