An entity class may be derived from another entity class. Although the subclass has its own properties and associations, it also inherits the superclass properties and associations. As a result, to persist a subclass object, we need to persist its own properties and associations, as well as those it inherits. The persisting should occur in a way that allows reconstruction of the original object later.
Databases, however, do not naturally provide a solution for persisting inheritance hierarchies. Therefore, each application may use its own solution for this purpose.
Let's continue our discussion with a simple example. The following figure shows a class diagram of an inheritance hierarchy with the
Person, Student, and ...