In OutSystems Platform you can extend the database model of your eSpace through the Extensions published in the Platform Server you are connected to.
Simply add to your eSpace a reference to the extension entities that integrate with tables of an external (foreign) database. From the OutSystems Platform point of view, those tables are called Foreign Entities.
How to Add an Extension Entity to your eSpace:
Once a foreign entity is added as a reference, you automatically have access to all the entity's actions, allowing you to manage its data: Create, CreateOrUpdate, Update, Get, GetForUpdate, and Delete.
If the entity has no primary key, only the Create action is available.
Be sure that this foreign entity handles Database data types supported by Service Studio. Check Integration Studio's documentation for more information.
In addition to the extensions defined in Integration Studio, OutSystems Platform has a special extension called ForeignEntities that contains all the entities declared as Foreign in versions lower than OutSystems Platform 3.1.
This extension is automatically created when you upgrade your Platform Server and is intended to facilitate the previous use of foreign entities.
About Extensions | Use Entity References | Use Extension Actions and Structures