>>Do select on FORCED and if it returns 0 record, run your regular select.
>>
>
>Is there a way to do this logic in one select?

I guess

SELECT * FROM mytable ;
  WHERE < Forced Condition > ;
UNION ALL ;
SELECT * FROM mytable ;
  WHERE < Other Condition >
   AND NOT EXISTS (SELECT * FROM mytable ;
  WHERE < Forced Condition > )