Mastering Database Management

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Relational Models

Entity-Relationship Model

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 Entity-Relationship (ER) Model is based on the notion of real-world entities and relationships among them. While formulating real-world scenario into the database model, the ER Model creates entity set, relationship set, general attributes and constraints.

 ER Model is best used for the conceptual design of a database.

 ER Model is based on −

 1. Entities and their attributes.

 2. Relationships among entities.

The ER(Entity Relationship) model defines the conceptual view of a database. It works around real-world entities and the associations among them. 

 Entity-

An entity can be a real-world object, either animate or inanimate, that can be easily identifiable. For example, in a school database, students, teachers, classes, and courses offered can be considered as entities.

Entities are represented by means of rectangles. Rectangles are named with the entity set they represent.