System triggers : Trigger « Trigger « Oracle PL/SQL Tutorial

There are a number of events where you can set system triggers such as

ON LOGON, ON LOGOFF, ON STARTUP, ON DROP, ON TRUNCATE, and so on.

You can even track when any DDL command (CREATE, DROP, ALTER, and so on) was executed in the database.

You may place system triggers at the database level or schema level.

At the database level, triggers fire for each event for all users.

At the schema level, triggers fire for each event for a specific user.