Exists clause: – The exists clause is used for testing whether the given set is empty or not. Exists on empty set return false while on non-empty set it returns true. The exists clause is used with where condition. An example of exists clause is –
Select emp1.ename from employee emp1 where exists(select emp2.city from company emp2 where emp2.ename=‘Anil’ and emp1.city=emp2.city);
In case of above example, ename column value of table employee are listed only when living city of both tables employee and company are same as living city of employee ‘Anil’.