4. What Is A Subclass? When Is A Subclass Needed In Data Modeling?

758 Words2 Pages

4.1. What is a subclass? When is a subclass needed in data modeling? A subclass is needed in data modeling, because it is the easiest way to explain the inheritance relationship between two classes. A subclass is a class that was originated from a new class. 4.2. Define the following terms: superclass of a subclass, superclass/subclass relationship, IS-A relationship, specialization, generalization, category, specific (local) attributes, and specific relationships. Superclass of a subclass – a class’s directs ancestor and all of the ascendant classes. Superclass/subclass relationship – a subclass comes from a superclass. A subclass and superclass go hand in hand. IS-A relationship – the relationship between a subclass and its superclass Specialization – process of classifying a class of objects into more specialized …show more content…

What is the difference between a specialization hierarchy and a specialization lattice? The difference is that in a specialization lattice a subclass can be a subclass in more than one class, whereas in hierarchy has that constraint. 4.8. What is the difference between specialization and generalization? Why do we not display this difference in schema diagrams? Generalization is process of extracting common characteristics from two or more classes and combining them into a generalized superclass. A Specialization is the reverse process of Generalization means creating new sub classes from an existing class 4.9. How does a category differ from a regular shared subclass? What is a category used for? Illustrate your answer with examples. A category differs from a regulated shared subclass because it has two or more super classes that represent entity types. 4.10. For each of the following UML terms (see Sections 3.8 and 4.6), discuss the corresponding term in the EER model, if any: object, class, association, aggregation, generalization, multiplicity, attributes, discriminator, link, link attribute, reflexive association, and qualified

Open Document