Explain the concepts of Generalization and Aggregation with appropriate examples. (RGPV 2019)
Entities with common attributes can be merged into a generic or super type entity by generalisation.
For example, the entity EMPLOYEE is a super type of Professor, Conductor, and Engineer.
The “IS-A” relationship between the subtype and the super type can be used to define generalisation.
For example, a Professor is an employee of the college.
Here, Professor, Principal and Engineer is subtypes. And, Employee is a supertype.
A super type can be a subtype in another relationsship.
Aggregation describes the formation of higher-level objects from lower level components.
For example, a car is made up of an engine, chasis, tiers and so on.
Aggregation can be defined in terms of an HAS -A-relationship between the subtype & supertype.