Databases

Hierarchy

Objects are instances of classes, e.g., JDoe is an instance of the class patient

Classes and objects form two different hierarchies.

• Class hierarchy (‘kind’): e.g., patient is a kind of person. A class inherits (and specializes) the characteristics of its parent class.
• Object hierarchy (‘part’): e.g., the object JDoe.height is a part of the object JDoe.

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