Strictly speaking: no.
A database can generally only be reached using database protocols using SQL and the datahub is based on OData over HTTPS.
If you want to access tables in Oracle databases in Mendix, you need either some app in between to convert it, or use the Database Connector
You could probably use the Database Connector to import data from Oracle to a specific entity. If you want to access the data in real time you should have an API available to your Oracle data that you can use.