This assessment item is to develop a conceptual data model based on the following case study. It relates to the unit learning outcome numbers 1 and 3 in the unit profile.
Assessment task
In this assignment, you are going to perform the entity-relationship data modelling based on the following application scenario.
The application scenario: Australasia Auto Services
Australasia Auto Services (AAS) is a prestigious dealer of cars based in Rockhampton, Queensland. Their main business is to provide professional maintenance services for various cars and also sells a wide range of new vehicles. With the boom of its business in recent years, AAS needs a relational database system to store information related to its business. In this assignment, your task is to design an entity relationship (E-R) data model for a database to be used by AAS in order to manage various information related to their business activities efficiently. You should read the case study carefully, making a note of all the entities you think are involved, and of their attributes. Consider the relationships between the entities as you do this. Although AAS hires many staff, each employee can be categorised one of three types: mechanic, salesperson, and administration staff. The duty of mechanic is to perform car maintenance service, while the salespersons are responsible for sales and the administration staff deal with a wide range of administrative jobs or miscellaneous tasks. Each employee at AAS has a unique employee number, and AAS maintains normal contact information about each employee. In addition, the technical trade level and expertise of mechanics, the number of year in sales experience for a salesperson, and the qualification of admin staff are to be recorded in the system. After a phone booking, a client will bring a car in for service on a specified date and the admin staff will record the car details that include the registration number, manufacturer, make, model, produced year and colour. The admin staff will also record a description of service requirement. Then the system will assign a unique identifier number for this service job. It is necessary to point out that the client’s car could be a car purchased from AAS, or it may be bought from somewhere else. For the former case, some relevant details such as the salesperson name, price, and warranty due date are required to keep in track. Usually each service job could be carried out by one or many mechanics. The data on service details such as which mechanics perform the service job, labour cost, part cost, date, start time and finish time must be recorded in the system. When a car is being repaired, it often involves replacing certain parts due to
various damages. For this reason, the mechanic may check its records in the database on a list of part types. Each type has a unique part identifier, a description, manufacturer or brand information, a price per unit and the quantity available in the stock. If parts are required to replace during service, the mechanic records the quantity of each type used into the database. From time to time, the clients may feel unsatisfactory on a service job done and therefore they may complain about service quality, expensive cost and other possible problems. If so, the lodged complaint should be recorded and processed appropriately by an admin staff, with a response addressed the outcome of investigation. Finally, AAS also wishes to maintain contact details for each client who requests service, including their residential address, contact phone, email and whether they are a senior citizen, who may receive some discount in a service.
You are required to develop an ER model to represent the information requirements for the application scenario (AAS) as described on last page.
Your ER model must: • show all necessary entities, attributes and relationships • show unique identifiers • show multi-valued attributes (also called repeating attributes), if any • show participation and cardinality • show associative entities, if appropriate • use the notation described in the set text • use consistent and appropriate naming for entities and attributes throughout
Some business rules or other aspects of the case study may not be clear to you when you read the case study. If this is the case, then you should either approach your lecturer or tutor for clarification, or you may simply make an assumption and then develop your ER model accordingly. For example, the case study might not mention all relevant participation information (also called minimum cardinalities). If so, you may make an assumption about what the minimum cardinalities might reasonably be, and then show these in your ER model accordingly. You should justify each assumption in terms of the business, for example: it is assumed that each customer must have at least one order because it is assumed that the business does not record customer details until the customer places an order. To get yourself started, ask yourself, 'If I were running this business, what things I would need to keep a list of?' Write those things down. For each thing, what information would you need to record about it?