Design a Generalization- Specialization hierarchy for a motor vehicle sales company. The company sells motor-cycles, passenger cars, vans, buses. Justify your placement of attributes at each level of the hierarchy. Explain why they should not be placed at a higher or lower level.
The process of generalizing entities, where the generalized entities contain the properties of all the generalized entities, is called generalization. In generalization, a number of entities are brought together into one generalized entity based on their similar characteristics. Specialization is the opposite of generalization. In specialization, a group of entities is divided into sub-groups based on their characteristics.
Here, Motor-Vehicle is the generalized entity, which has some specialized entity like Motor-Cycle, Vans, Buses, and Passenger Cars. These specialized Entities have their own specialized Model. But all entities have the common attributes i.e. Registration number as their generalized entity, Motor-Vehicle. The Relationship has been presented here via ISA Relationship.
What are the differences between Primary Index, Secondary Index, and Clustering Index?
Define a Foreign key. Why is the concept needed? How does it play a role in the join operation?
