Change Oracle Database Character Set

To change the character set of an Oracle database, you can follow these steps:

1. Make sure to back up the database before changing the character set to prevent any data loss.
2. To confirm the current character set, you can use the following SQL statement to query the character set of the current database.
3. Retrieve the value from the nls_database_parameters table where the parameter is ‘NLS_CHARACTERSET’.
4. Stop database service: The database service needs to be stopped before modifying the character set.
5. Change the NLS_CHARACTERSET parameter: You can modify the character set of the database using the ALTER DATABASE statement, for example changing it to UTF8.
6. Change the character set of the database to UTF8.
7. Modify the NLS_LENGTH_SEMANTICS parameter (optional): To change the NLS_LENGTH_SEMANTICS parameter, you can use the following statement to modify it to either BYTE or CHAR.
8. Change the character set of the database to UTF8.
9. Start the database service: After modifying the character set, restart the database service.
10. Validate if the character set has been modified: You can verify if the modification was successful by using the SELECT statement to query the database’s character set again.

Please be aware that changing the character set of the database may affect existing data and applications, it is recommended to backup and test beforehand.