Concepts of Entity Relationship Diagram( ER diagram)

Entity Relationship Model:

An Entity – Relationship model (ER model) is an abstract way to describe a database. It is a visual representation of different data using conventions that describe how these data are related to each other.
There are three basic elements in ER models:

• Entities are the “things” about which we seek information.
• Attributes are the data we collect about the entities.
• Relationships provide the structure needed to draw information from multiple entities.

Symbols used in E-R Diagram:

• Entity – rectangle
• Attribute -oval
• Relationship – diamond
• Link - line