The OBJECT_ID pseudocolumn returns the object identifier of a column of an object table or view. Oracle uses this pseudocolumn as the primary key of an object table. OBJECT_ID is useful in INSTEAD OF triggers on views and for identifying the ID of a substitutable row in an object table.
Note:
In earlier releases, this pseudocolumn was calledSYS_NC_OID$. That name is still supported for backward compatibility. However, Oracle recommends that you use the more intuitive name OBJECT_ID.See Also:
Oracle Database Application Developer's Guide - Object-Relational Features for examples of the use of this pseudocolumn