You can set the database in
quiesced mode by the following command.
alter system quiesce restricted;
After running this command all sessions except the ones that have DBA privileges will hang there.
Also you can enable the
restricted session like this:
alter system enable restricted session;
After running this command, just the users that have enough privileges can connect to the database.
My question is: are there any other differences between them? When should use them?