ER-Diagram

ER-Diagram

ER Diagram presents data visually on how they are related to each other. This model follows separate notations for representing data into entities, attributes and relationship between the entities.

ER-Modeling Diagram Notations

Entities, Attributes and Relationship forms the components of ER Diagram and the defined symbols and shapes are summarized below in Table 3.6

Example

Fig 3.12 is an example of ER Diagram for the scenario of School Management System. We have many entities like Parent, student, Admin, Teacher, class and subjects. 

The attributes of few entity is given below:

Parent – Name, Id, Fname, Lname.

Student – Id, Name, Fname, Lname.

Teacher – Name, Id, Phone#, Address.

The relationships that exist between the entities are as follows:

• Parent HAVE Student

• Admin ENROLLS Student

• Admin HIRES Teacher

• Admin ADDS Subject

• Teacher TEACHES Subject

• Teacher IS ASSIGNED TO Class

Key Attributes are listed with underline.