Nested Sub-Queries

A query with in a Sub-Query is nothing but Nested Sub Query.

Syntax:-

SQL>Select ,  … from  where  (select  from where  (select  from where ));  
 
Example:-
Display the Manager of ‘TURNER’ and display the ‘MANAGER’ of ‘TURNER’ manager.
 
SQL> select *from EMP where empno in (select mgr from EMP where empno in (select mgr from EMP where ename ='TURNER'));