Create additional databases using Oracle Database Configuration Assistant (Oracle DBCA).
Oracle Universal Installer (OUI) runs Oracle DBCA and creates a starter database for you as part of the single-instance Oracle Database installation. If you want to create additional databases, then you can launch Oracle DBCA as a standalone tool anytime after the Oracle Database installation.
You can run Oracle DBCA in interactive mode or silent mode.
To run Oracle DBCA in interactive mode:
$ cd $ORACLE_HOME/bin $ ./dbca