Match Date Function Help

I am trying to create a rule to expressing the below logic:

If input variable “date” is a match in the database then output variable Family as Yes. For instance, if i have a database with 10,000 contracts, I want to group all contracts under the same family and mark as family “Yes”. I’m not familiar with JUEL and haven’t any luck in finding a proper example.

I used an exact date and it works but the logic does not scale. Any advice is greatly appreciated.