SQL Guide : Using SQL for database administration : Managing user privileges and roles : Granting administrator privileges to a user
  
Granting administrator privileges to a user
GRANT SYS_ADMIN_ROLE TO username ;
The following example grants administrator privileges to CALVIN, who now has all privileges to all tables:
GRANT SYS_ADMIN_ROLE TO CALVIN;
You may also want to grant a user the right to perform data synchronization operations. To do this, execute the command:
GRANT SYS_SYNC_ADMIN_ROLE TO HOBBES
Note If the autocommit mode is set OFF, you need to commit your work. To commit your work use the following SQL statement: COMMIT WORK; If the autocommit mode is set ON, the transactions are committed automatically.
See also
Managing user privileges and roles