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CS157a
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HW Assignments:
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Practice Exams:
  [Mid1] [Mid2] [Final]

CS157a Fall 2005Practice Final

To study for the midterm I would suggest you: (1) Know how to do (by heart) all the practice problems. (2) Go over your notes three times. Second and third time try to see how huch you can remember from the first time. (3) Go over the homework problems. (4) Try to create your own problems similar to the ones I have given and solve them. (5) Skim the relevant sections from the book. (6) If you want to study in groups, at this point you are ready to quiz each other. The practice final is below. Here are some facts about the actual final: (a) The final will be in class Dec 14 from 12:15pm to 2:30pm for Sec3 and Dec 16 from 12:15pm to 2:30pm for Sec4. (b) It is closed book, closed notes. Nothing will be permitted on your desk except your pen (pencil) and test. (c) You should bring photo ID. (d) There will be more than one version of the test. Each version will be of comparable difficulty. (e) If your cell-phone or beeper goes off you will be excused from the test at that point and graded on what you have done till your excusal. (f) One problem (less typos) on the actual test will be from the practice test.

[Student Generated Solutions-PDF]

1. Give the four design guidelines we had from class for a good decomposition of a universal relation into tables.

2. Using our inference rules for FDs prove that:

{A->EB, B-->C, C-->D} |= ZA --> ZD

3. Let F={A-->B, AB-->C, EC-->D }. Compute EA⁺.

4. Give a set of FDs so that to compute the minimal cover you need to do something for each of the steps of the algorithm.

5. Give a set of FDs and a decomposition which is in 3NF but not in BCNF.

6. Define: dependency preserving property and lossless join property. In each case give two example decompositions and FDs: one with the property, one without the property.

7. Let F = {AB-->C, C-->D, D--> B} and let R ={ABCDE}. Use the algorithm from class, showing and explaining each step, to decompose R into 3NF schemas with both the lossless join property and with the dependency preserving property.

8. Give an example of a decomposition with respect to a set of dependencies which is in BCNF but not in 4NF.

9. Give an example of a decomposition with respect to a set of dependencies which is in 4NF but not in 5NF.

10. Briefly describe the database application system life cycle.