Explain the concepts of Generalization and Aggregation with appropriate examples.

Explain the concepts of Generalization and Aggregation with appropriate examples. (RGPV 2019)

Ans. Generalization:

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:

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.