merge two columns

qq I have two different date columns in oracle I want to be able to merge them to get a date prompt that will cover the two different date

CASE Opportunity."Close Date" WHEN  Opportunity.DATE_28 END

 

CASE Opportunity."Close Date  this is  the opportunity expected  close date

 

Opportunity.DATE_28   this is the actual close date

 

I need to look at opts by both  expected close date and actual close date

And need to create a prompt to do this that will have both dates in the prompt