# Practical 05: Entity-Relationship Diagram (ERD)


Ensure that you have gone through Lecture 5: Structuring System Data Requirements before attempting this practical.

# Theroretical Questions

  1. State whether there is a one-to-one, one-to-many, or many-to-many relationship for the following pairs of related entities. Use the notation introduced in the text to draw a diagram for each of the relationships.

    • Employee and Project
    • Student and Course
    • Course and Section
    • Customer and Order
    • Patient and Bed
  2. Distinguish the following types of data models:

    • Conceptual Data Model
    • Logical Data Model
    • Physical Data Model

# Hands-On Tasks

# Task 1

Car Dealership System

The dealership sells both new and used cars, and it operates a service facility. Base your design on the following business rules:

  • A salesperson may sell many cars, but each car is sold by only one salesperson.
  • A customer may buy many cars, but each car is bought by only one customer.
  • A salesperson writes a single invoice for each car he or she sells.
  • A customer gets an invoice for each car he or she buys.
  • A customer may come in just to have his or her car serviced; that is, a customer need not buy a car to be classified as a customer.
  • When a customer takes one or more cars in for repair or service, one service ticket is written for each car.
  • The car dealership maintains a service history for each of the cars serviced. The service records are referenced by the car's serial number.
  • A car brought in for service can be worked on by many mechnaics, and each mechanic may work on many cars.
  • A car that is serviced may or may not need parts (e.g., adjusting a carburetor or cleaning a fuel injector nozzle does not require providing new parts).

Construct an Entity-Relationship Diagram (ERD) for the given system.


Complete the given practical and submit it as your lecture attendance for Week 6.

Last Updated: 7/9/2021, 12:34:40 AM