Originally posted by toshi

Now what I'm confused about is the 'IMMEDIATE' clause when used with 'DISCONNECT SESSION' and 'KILL SESSION'. Or maybe there is no difference but I just want to know.

Thanks for your reply
There is difference. With "kill" you mark the session as dead, rollback ongoing transactions, release all session locks, and partially recover session resources. With "disconnect" you only destroy the dedicated process (or the circuit).