Question 1 (ER Model)

Design an Entity-Relationship diagram that models a department management system and considers the requirements listed below. That means that you have to identify suitable entity sets, relationship sets, at- tributes, keys of entity sets (if not specified), and so on. Further, add the cardinalities (1:1, 1:m, m:1, m:n) to the relationship sets and write down your assumptions regarding the cardinalities if there could be a doubt. Consider the following requirements about a car dealership system: An employee has an ID which is unique, email address, name, date of birth, and age. Age is a derived attribute. There are two types of employees in a system: Salesperson and Mechanic. Employees belong to a department that has a departmentID, name, and the chair name. 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 customer has an email, name, date of birth, age (derived), and phone number. A salesperson writes a single invoice for each car he or she sells. An ID, date, and price are stored in the invoice. A customer gets an invoice for each car he or she buys. When an invoice is written, the information of the car is stored. A serial number, make, model, color, and year are stored for each car. A customer may come in to have his or her car serviced. When a customer takes one or more cars in for repair or service, a mechanic writes one service ticket for the owner of the car. Date, reason for service, mechanics who work on, and price of the service are stored. A car brought in for service can be worked on by many mechanics, and each mechanic may work on many cars.