An object-relational database system puts an object oriented front end on a relational database (RDBMS).
When applications interface to this type of database, it will normally interface as though the data is stored as objects.
However the system will convert the object information into data tables with rows and columns and handle the data the same as a relational database.
Likewise, when the data is retrieved, it must be reassembled from simple data into complex objects.
Extending the Oracle 21c Server with Object Types
Oracle 21c expands current datatypes and adds new datatypes to support larger data and openness in the database:
User-defined types or object types
Collection types such as VARRAY (varying array) and TABLE (nested table)