kirangsv

 Profile Answers by kirangsv 

• Jun 2nd, 2008

 

Co-related sub-query:- The main differencre between subquery and co-related subquery is that in subquery child query is executed first n then parent,but in co-related subquery main query is executed first(even though parenthesis are present) and then child query.

Example of co-related subquery

select dname from dept where exists
(select deptno from emp
where dept.deptno=emp.deptno);

select dname from dept where not exists
(select deptno from emp
where dept.deptno=emp.deptno);