How do you set the default tablespace in Oracle?

To set the default tablespace, follow these steps:

1. Log in to the system user of the Oracle database.
2. Retrieve the property value for ‘DEFAULT_PERMANENT_TABLESPACE’ from the database_properties table.
3. Change the default tablespace for the database to a new one.
4. Retrieve the value of the property called ‘DEFAULT_PERMANENT_TABLESPACE’ from the database_properties table.

Please note that setting the default tablespace should be done under a system user and with appropriate permissions. Additionally, changing the default tablespace may impact existing users and objects, so caution is advised.