Assignment 1: Entity-Relationship Data Model

Start date 30 August, Due beginning of class 11 September.

Exercises from the Book

Complete the following exercises from the book:

• 2.4. If you reach a point where you feel there is not a clear choice as to the right way to do this, document the assumptions you made and how they are reflected in the database design.
• Produce relational tables corresponding to Figure 2.10 in the book.

If you want some easier ones to practice with, the odd-numbered exercises in the book have answers available at the book web site.

Relational to ER

Given the following relational database:

Course_TA(Course, Name)
Assignment_Graded(Course, Name, Assignment_Number, Number_Of_Students, Average_Score)
TA(name, Office, Office_Hours)
Course_Info(Course, Room, Time)

1. Give two different Entity-Relationship Diagrams that could represent this relational database (i.e., would convert to this relational database). Use a weak entity set in at least one of them.
2. Describe the difference between your two ER diagrams, in terms of the real-world meaning of what can and cannot be represented. Why would you choose one or the other? Are there policies that you think questionable that are enforced by the above relational database?
3. Note that in the Course_TA relationship, both Course and Name are needed to form a key. Describe what would change if we were to make only one of those a key (i.e., describe the real-world changes that would have to happen happen in the way course assignments, grading, etc. are done would lead to one or the other being a key.)

Turning in the assignment

Electronic submission preferred. I'll be setting something up in a bit (suggestions for your choice welcome - WebCT? Others?) For these assignment, send to cs541@mentor.ics.purdue.edu. Pdf is the safest for capturing non-text, please check with me for formats other than txt or pdf. Hard copy is acceptable as well, please hand in at the beginning of class.