Learn Oracle SQL : The Hierarchical Query Clause by Rocky Jagtiani Oracle Certified Associate I train on Oracle Certification from last 7 years For understanding the Hierarchical Query Clause , make sure of : 1> Installing Oracle-11g ( steps of installation and Oracle-11g download copy is here , please see Oracle SQL - Pl/SQL > downloads section ). By the way any version from 9i and upwards would do. 2> Reading each and every step. 3> & finally Executing as you read on. Lets create some data sets to play with : create table hierarchy( empno int not null unique, ename varchar2(20) not null, Job varchar2(20) not null, mgr int, deptno int not null ); // Add some records to the above table // Assume deptno : 100 -> HR and 101 -> Training insert into hierarchy values(1,'Simran', 'director', null, 100); insert into hierarchy values(2,'Rocky', 'Training-Head', 1, 101); insert in...