E-R Diagram

E-R Model:

ER model is a detailed logical representation of entities, association and data elements for an organisation. This technique is used in database design that helps to describe how entities in an organisation are related to another.

It includes three features for describing data-

(1)           Entity:

It can be person, place, events to the organisation & about which data are captured, stored or processed.

(2)           Attribute:

Various types of data elements that describe an entity are known as attributes.

For Ex:

An entity employee can have attributes such as name, date of birth, address etc.

(3)           Relationship:

An association of several entities in an ER model is called relationship.

Different symbols used in ER model: