There are 4 modes can be used to shutdown the Oracle database. To initiate the Oracle database shutdown, you can use the sqlplus shutdown command. In order to do this, you must be connected as SYSDBA or SYSOPER.
Shutdown with NORMAL mode
If user issued the shutdown with the normal option, the Oracle will not allowed new connections coming in. Oracle will waits for all current connected users to disconnect from the database before the shutdown process begin.
SQL> shutdown normal
Shutdown with IMMEDIATE mode
The IMMEDIATE mode will shutdown the Oracle database immediately. Users will be forcefully to log off from the database.
SQL> shutdown immediate
Shutdown with TRANSACTIONAL mode
TRANSACTIONAL mode will not log off the users thus prevent users from losing their works. Active/current users will not be kick out.
SQL> shutdown transactional
Shutdown with ABORT mode
You are advised to use this ABORT mode when all the above shutdown modes are not working. This mode will shutdown the Oracle database instantaneously and abort/kick out all the active users from the database.
SQL> shutdown abort
