You may create a database using one of three tools:  SQL *Plus: The SQL *Plus starting command may be used to start an Oracle database instance.  Oracle Enterprise Manager: This is a system management tool that may also be used to start the Oracle database. It offers an all-in-one solution for controlling your heterogeneous environment. Even if the database is halted you can still log in to OEM. It will display the Startup button after detecting the condition of the down database.  Recovery Manager: RMAN is also known as the RMAN repository, which is linked with the TARGET keyword and is also a database on which RMAN executes backup and recovery operations in the database's control file.