Question

[1] Please draw an ERD based on the following description.

The requirements collection and analysis phase of the database design process has provided the following data requirements for a company called Reliable Rentals, which rents out vehicles (cars and vans).

The Company has various outlets (garage/offices) throughout Glasgow.

Each outlet has a number, address, phone number, fax number, and a manager who supervises the operation of the garage and offices at each site.

Each site is allocated a stock of vehicles for hire, however, individual vehicles may be moved between outlets, as required. Only the current location for each vehicle is stored. The registration number uniquely identifies each vehicle for hire and is used when hiring a vehicle to a client.

Clients may hire vehicles for various periods of time (minimum 1 day to a maximum 1 year). Each individual hire agreement between a client and the Company is uniquely identified using a hiring number. Information stored on the vehicles for hire includes: the vehicle registration number, model, make, engine size, capacity, current mileage, date MOT due, daily hire rate, and the current location (outlet) of each vehicle.

The data stored on a hire agreement includes the hire number, the client’s number, name, address, and phone number, date the client started the hire period, date the client wishes to terminate the hire period, the vehicle registration number, model and make, the mileage before and after the hire period. After each hire, a member of staff checks the vehicle and notes any fault(s). Fault report information on each vehicle is stored, which records the name of the member of staff responsible for the check, date checked, whether fault(s) were found (yes or no), the vehicle registration number, model, make and the current mileage.

The Company has two types of clients: personal and business. The data stored on personal clients include the client number, name (first and last name), home address, phone number, date of birth, and driving license number. The data stored on business clients include the client number, name of business, type of business, address, telephone, and fax numbers. The client number uniquely identifies each client and the information stored relates to all clients who have hired in the past and those currently hiring a vehicle.

Information is stored on the staff based at various outlets including staff number, name (first and last name), home address, home phone number, date of birth (DOB), sex, National Insurance Number (NIN), date joined the Company, job title, and salary. Each staff member is associated with a single outlet but may be moved to an alternative outlet as required, although only the current location for each member of staff is stored.

Answer 1

The ER diagram of the given scenario is below. It consist of 4 entities connected via 4 relationship. Entity client has generalization into personal and business client. All attributes of entity client will be there in its sub entity (personal, business) plus some additional entities.

Each entity has certain set of attributes and primary key is mentioned as underlined attribute.

Cardinality is shown using crow's foot notation.