SQL & PL/SQL

Hi All,

I am trying to understand CONNECT BY Level/prior/root. But i find it difficult to decipher what it actually does. I believe this is very useful method provided by oracle and can have multiple usages. can anyone please help me on this.

I googled about it but everywhere i could find only employee and manager problem, which will be solved by below query.

 SELECT employee_id, last_name, manager_id
   FROM employees
   CONNECT BY PRIOR employee_id = manager_id;

But if we just want query like below we can get the employee and its manage without CONNECT BY .

SELECT employee_id, last_name, manager_id
   FROM employees;

Other query is got for connect by is below, but couldn't understand it also:

 select SYSDATE-41 + level - 1 the_date
                            from dual
                          connect by level <= SYSDATE - SYSDATE-41 + 1

Please help me .

Edited by: J2EE_Life on Dec 6, 2011 8:12 AM