Test for Empty Relations

1. The exists construct returns true if the argument subquery is nonempty.
2. Find all customers who have a loan and an account at the bank.

    select cname
   
   		 from borrower
   
   		 where exists (select *
   
   		 		 		 		 from depositor
   
   		 		 		 		 where depositor.cname = borrower.cname)