CS430/630 – Homework 6
50 points
Due May 08 BEFORE CLASS
Instructions: Please submit paper copies (either typeset or hand-written copies are fine, as long as the
hand writing is clear).
Question 1 (15 points)
Suppose you are given a relation R with four attributes ABCD and the following set of FDs: AB→C, BC→D.
a. Identify the candidate key(s) for R (recall that keys must be minimal)
b. Determine if R is in BCNF, 3NF, or none of the above. If it is not in BCNF, decompose it into a
set of BCNF relations.
Question 2 (15 points)
Suppose you are given a relation R with four attributes ABCD and the following set of FDs: BC→A, AB→C,
C→DA.
a. Identify the key(s) for R (recall that keys must be minimal)
b. Determine if R is in BCNF, 3NF, or none of the above. If it is not in BCNF, decompose it into a
set of BCNF relations.
Note: For both questions, recall that it is not sufficient to consider the set of FDs that are given, but also
its closure.
Question 3 (20 points)
Show the grant diagrams after steps 7 and 8 of the sequence of actions below, where A owns the relation
on which the privilege p is assigned. Can C still exercise privilege p after step 8? What about E?
Step Executed by Action
1 A GRANT p TO B
2 A GRANT p TO C WITH GRANT OPTION
3 C GRANT p TO D WITH GRANT OPTION
4 A GRANT p TO D WITH GRANT OPTION
5 D GRANT p TO B WITH GRANT OPTION
6 B GRANT p TO C
7 D GRANT p TO E
8 A REVOKE p FROM C CASCADE