HW #3 Solution



Turn in your answers via a pdf file uploaded to eCampus, and turn in a hard copy of your answers at class time on the due date. Your turnin should include your signature below the Aggie honor code statement: An Aggie does not lie, cheat or steal or tolerate those who do.

This HW will help you understand the concept of E/R relationship modeling. It also gets us started on the project I have in mind for this semester!

1. Visit the website: http://www.databaseanswers.org/index.htm, and click Data

Models” in the menu bar.

(a) Read the tutorial slide notes (3 thru 10) starting at http://www.databaseanswers.org/tutorial4_db_schema/tutorial_slide_3.htm On slide 4, how does the writer encourager the reader to see the world? What is der_order_price on slide 6?

On slide 7, he identifies a benefit of storing addresses in a separate table. What is it? (b) Study the diagram for Bank checking accounts http://www.databaseanswers.org/data_models/banking_checking_accounts/index.htm How would you modify it so that a customer could have more than one address?

Draw your changes using a tool like Dia. https://sourceforge.net/projects/dia installer/, an Eclipse drawing tool like UMlet, or some other drawing tool.

2. Study the diagram at this link: http://www.databaseanswers.org/data_models/online_exams/index.htm a. Write a CREATE TABLE statement for table Valid_Answers

b. A professor uses an application to prepare an exam. What database tables would an application SELECT from to help a Professor ‘look at’ a previous exam?

c. A student uses an application to take an exam. What tables would the application query to administer an exam?

d. As a student worked thru the exam, what tables would be modified by inserting or updating records?

3. Using the crows foot‘ ERD notation on slide 25 (Chp 4 lecture), redraw the class diagram given in slide 21 (Chp 4 lecture). Use a drawing tool such as Dia, or an Eclipse plugin like UMlet, or some other drawing tool.

4. PROJECT DIAGRAMS. From the project discussion in class, create a Class Diagram like that discussed in Chp 4 slides. Develop a preliminary class diagram, then reify it per the lecture slides to make it into an ERD. Turnin both diagrams—the original

and final diagrams. Show the cardinality of relationships and label the arrows in the ERD. I suggested a drawing package: http://diainstaller.de/index_en.html, but you can also use an Eclipse plugin, or other drawing tool. These Diagrams counts as 100 points toward your Project grade, which will have other components to it as the Project evolves over the semester.