ALTER SYSTEM

ALTER SYSTEM statement to dynamically alter your Oracle Database instance. The settings stay in effect as long as the database is mounted.

Privilege: We must have ALTER SYSTEM privilege

REGISTER Clause : Specify REGISTER to instruct the PMON background process to register the instance with the listeners immediately.

 If you do not specify this clause,PMON will automatically re-register time to time.

SUSPEND | RESUME :

SQL> ALTER SYSTEM SUSPEND;

System altered

SQL> SELECT DATABASE_STATUS FROM V$INSTANCE;

DATABASE_STATUS

---------

SUSPENDED

SQL> ALTER SYSTEM RESUME;

System altered

SQL> SELECT DATABASE_STATUS FROM V$INSTANCE;

DATABASE_STATUS

---------

ACTIVE