You may create a database with one of three tools:
SQL *Plus: The SQL *Plus starting command can be used to start an Oracle database instance.
Oracle Enterprise Manager: This is a system management tool that can also be used to start up an Oracle database. It offers an all-in-one solution for managing your complex environment. Even if the database is down, OEM can still be accessed. By detecting the condition of the down database, it will offer you the Startup button.
RMAN stands for Recovery Manager and is associated with the TARGET keyword, which is also a database on which RMAN executes backup and recovery operations in the database’s control file.