CS336 - Principles of Information and Data Management - Homework 1 - Solved

Exercise 1. Notown Records has decided to store information about musicians who perform on its albums (as well as other company data) in a database. The company has wisely chosen to hire you as a database designer.

•         Each musician that records at Notown has an SSN, a name, an address, and a phone number. Poorly paid musicians often share the same address, and no address has more than one phone.

•         Each instrument used in songs recorded at Notown has a name (e.g., guitar, synthesizer, flute) and a musical key (e.g., C, B-flat, E-flat).

•         Each album recorded on the Notown label has a title, a copyright date, a format (e.g., CD or MC), and an album identifier.

•         Each song recorded at Notown has a title and an author.

•         Each musician may play several instruments, and a given instrument may be played by several musicians.

•         Each album has a number of songs on it, but no song may appear on more than one album.

•         Each song is performed by one or more musicians, and a musician may perform a number of songs.

•         Each album has exactly one musician who acts as its producer. A musician may produce several albums, of course.

Draw an ER diagram based on the preceding description of the situation that the Notown database must model. Be sure to indicate all key and cardinality constraints and any assumptions you make. Identify any constraints you are unable to capture in the ER diagram and briefly explain why you could not express them.

Exercise 2. Computer Sciences Department frequent fliers have been complaining to Dane County Airport officials about the poor organization at the airport. As a result, the officials decided that all information related to the airport should be organized using a DBMS, and you have been hired to design the database. Your first task is to organize the information about all the airplanes stationed and maintained at the airport. The relevant information is as follows:

•         Every airplane has a registration number, and each airplane is of a specific model.

•         The airport accommodates a number of airplane models, and each model is identified by a model number (e.g., DC-lO) 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 expertise may overlap with that of other technicians. This information about technicians must also be recorded.

•         Traffic controllers must have an annual medical examination. For each traffic 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 identified by a social security number.

•         The airport has a number of tests that are used periodically to ensure that airplanes 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 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 the airplane received on the test.

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 (in English).