Entity Relationship and It's Components

 

What is an Entity Relationship Diagram?

• An Entity-relationship Diagram (ER Diagram) describes the relationship of entities that need to be stored in a database.    

• ER Diagram is mainly a structural design for the database. It is a framework using specialized symbols to define the relationship between entities.  

• ER diagram is created based on three main components entities, attributes, and relationships.

The following diagram show case in two entities student and course and the relationship. The relationship describe between student and course is many to many. As a course can be octed by several student . As  a student can more than one course. Here student is the entities  and it’s possessive attributes that is student id , student name, and student age. And the course attributes such as course id, and course name . 

 

Why is has been so popular?

• Helps us conceptualize the database and help us know which fields need to be embedded for a particular entity.    

• ER Diagram gives a better understanding of the information to be stored in a database.

• Reduces complexity and saves time which allows you to build databases quickly.

• Helps to describe elements using Entity Relationship model.

 

Symbol Used in ER Diagram

Component of ER Diagram