Question

Question 3: EER Diagrams

You accepted a position as a database application programmer at the DriveAway electric scooter rental company in Bora Bora island. As a first step, you are asked to create an EER diagram that captures the following business rules:

Typically, DriveAway’s customers are tourists that visit the island for periods ranging from one week to 6 months. Customers are identified by their client number, and we also record their addresses while on Bora Bora. In addition, the passport information and home addresses of all customers are stored.

a) A customer rents one or more scooters from the company and a scooter may be rented by many customers, obviously for rental periods which do not overlap.

b) The shortest period that a scooter may be rented is for 8 hours, and the longest contract is for 1 month.

c) There are three locations (shops) on the island where a customer may rent a scooter from. The customer is always required to return a scooter to the location where he rented it from.

d) DriveAway has a fleet of 50 electric scooters. For each scooter, we keep information about the color, the year purchased, the current kilometer reading, the brand name, the model, the power, the voltage, the charging time and the range per charge.

e) Each scooter needs to be registered and the registration has to be renewed every year, at the traffic department of French Polynesia, which is located in Papeete (the capital of French Polynesia).

f) A scooter is serviced at a regular interval, usually after every 800 kilometers of travel. Sometimes a scooter may break down and then it needs to be repaired. There is one mechanic on the island who services and repairs all the scooters. Note that she is not employed by DriveAway.

g) DriveAway also maintains 50 charging stations, throughout the island. The customers may use these stations to recharge their scooters. This service is free of charge and available 24/7.

h) An employee is responsible for completing all the necessary forms when a customer rents a scooter.

i) There are 15 employees that work for DriveAway, including two (full‐time) supervisors and two (part‐time) charging station repairmen. The company further employs one (part‐time) accountant who works from home. The other employees are full‐time customer consultants that also act as receptionists. These employees are deployed at any one the three shops, as need be. Full‐time employees receive a salary and benefits such as health care, while part‐time employees are paid by the hour and do not receive any benefits. All employees are required to pay income tax.

Your Task:

Create an EER diagram that models the DriveAway database. Your model should include entities, relationships as well as all attributes. Remember to state all your assumptions.

I do not know how to represent b), c), e), f), could you explain those in detail?

Answer 1

Answer: EER diagram power color reg no year of buy rent hours rent location cust no reg date scooter_mode Rent Scooter cust name voltage brand_of_scooter cust passport rent_rate retur date charging time emp id Hires Belongs_to paid_tax ISA deployed_at Drive way has ull time art time salary Charging station insurance hour_rate ocation

Explanation Entities: Customer, Scooter, Charging station, Drive way, Employee, Full time, Part time Attributes: The customer contains three attributes, scooter contains nine attributes, charging station contains one attribute, part time contains one attribute, full time contains three attributes and employee contains two attributes Relation: Customer and Scooter contain one to many relation, employee and drive way contains one to one relation and then drive way and charging station contains one to one relation. Explanation for b), c), e), f): b) The entity is "Scooter", where the scooter is rented for eight hours the contract is long then it will be rented for one month. c) The entity is "Scooter" and "Customer". The island contains three shops where the customer is rented from. The customer should return the scooter where they rented from. e) The entity is "Scooter". The scooter should be registered and renewed each and every year at f. The entity is "Scooter" and "Driveway". The scooter must be serviced every 800 kilometers. Occasionally the scooter may repair, there is one machine which repair the scooter is island.