how to change the database name

Follow these steps to rename a database:
1. Start by making a full database backup of your database (in case you need to restore if this procedure is not working).

2. Execute this command from sqlplus while connected to 'SYS AS SYSDBA':

ALTER DATABASE BACKUP CONTROLFILE TO TRACE RESETLOGS;
2. Locate the latest dump file in your USER_DUMP_DEST directory (show parameter USER_DUMP_DEST) - rename it to something like dbrename.sql.

3. Edit dbrename.sql, remove all headers and comments, and change the database's name. Also change "CREATE CONTROLFILE REUSE ..." to "CREATE CONTROLFILE SET ...".

4. Shutdown the database (use SHUTDOWN NORMAL or IMMEDIATE, don't ABORT!) and run dbrename.sql.