Develop an EER model for the following situation. You need to make your own (rea

Question

Develop an EER model for the following situation. You need to make your own (reasonable) assumptions regarding the relationship cardinality if it is not explicitly indicated. Show your assumptions in your solution. You need to indicate which attribute you choose for the identifier of each entity type. You may create an identifier attribute if needed.

A technology company provides offerings to its customers. Offerings are of two separate types: products and services. Offerings are identified by an offering ID and an attribute of description. In addition, products are described by product name, standard price, and date of first release; services are described by name of the company’s unit responsible for the service, conditions of service, and the service type. There are repair, maintenance, and other types of services. A repair service has a cost and is the repair of some product offered by the company; a maintenance service has an hourly rate. The company wants to keep track of repair services on products with repair date and a short description of the issue. Some products may never require repair, but there are many potential repair services for a product. A customer may purchase an offering, and the company needs to keep track of when the offering was purchased and the contact person for that offering with the customer. Unfortunately, not all offerings are purchased. Customers are identified by customer ID and have descriptive data of name, address, and phone number. When a service is performed, that service is billed to the customer. When a customer is billed for a service (some customers may never require a service), the company wants to keep track of the service date, the due day of the bill, and the amount due.

Explanation / Answer

Every airplane has a registration number, and each airplane is of a speci c model.

The airport accommodates a number of airplane models, and each model is iden-

ti ed by a model number (e.g., DC-10) and has a capacity and a weight.

A number of technicians work at the airport. You need to store the name, SSN,

address, phone number, and salary of each technician.

Each technician is an expert on one or more plane model(s), and his or her exper-

tise may overlap with that of other technicians. This information about technicians

must also be recorded.

Trac controllers must have an annual medical examination. For each trac

controller, you must store the date of the most recent exam.

All airport employees (including technicians) belong to a union. You must store

the union membership number of each employee. You can assume that each

employee is uniquely identi ed by the social security number.

The airport has a number of tests that are used periodically to ensure that air-

planes are still airworthy. Each test has a Federal Aviation Administration (FAA)

test number, a name, and a maximum possible score.

The FAA requires the airport to keep track of each time that a given airplane

is tested by a given technician using a given test. For each testing event, the

information needed is the date, the number of hours the technician spent doing

the test, and the score that the airplane received on the test.

1. Draw an ER diagram for the airport database. Be sure to indicate the various

attributes of each entity and relationship set; also specify the key and participation

constraints for each relationship set. Specify any necessary overlap and covering

constraints as well

2. The FAA passes a regulation that tests on a plane must be conducted by a tech-

nician who is an expert on that model. How would you express this constraint in

the ER diagram

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