Entity Relationship Diagram

Introduction Definition: Entity-relationship diagram is a data-modeling technique that visualises entities, the attributes of the entities, and the relationship between entities, within an information system.

Components Entity Attributes Relationship Cardinality Participation Constraint

Cardinality Definition: The number of elements in a set or other grouping, as a property of that grouping

Participation Constraint Definition: specifies whether the existence of an entity depends on its being related to another entity via the relationship type

Relationship One to one One to many Many to many

ER Diagram using Crow’s Foot Notation

Crow’s Foot Notation

ER Diagram using Chen’s Notation

Chen’s Notation

Chen’s notation