Hi Christiana,
In this case I think you have two options that I can think of:
You can find more information here: https://docs.mendix.com/howto/integration/execute-an-sql-statement-on-an-external-database
You can do this with NPEs (Non Persistent Entities) and the database connector. NPEs only live in memory, and are not persisted to your local database. Retrieve your data from the oracle database into NPEs, edit them in a page, and then save them back to the oracle database using the database connector.