The questions can come in any order, so make sure you are selecting right option for all questions.
1. A table is in BCNF if it is in 3NF and if every determinant is a ___________ key.
(c) Super
2. R is decomposed or divided into R1 with FD { f1 } and R2 with { f2 }, then the decomposition is not dependency preserving when
(b) f1 U f2 is a subset of F
3. What does BCNF stand for in Database Normalization?
(b) Boyce–Codd Normal Form
4. Consider the relation R (X,Y,W,Z,P,Q) and the set F = {XY -> W, XW -> P, PQ -> Z, XY -> Q}.
R is decomposed into R1(Z,P,Q) and R2(X,Y,W,P,Q).
Which of the following is true about R?
(d) Both lossless decomposition and dependency preserving decomposition
| Stu_ID | Stu_Branch | Stu_Course | Branch_Number | Stu_Course_No |
|---|---|---|---|---|
| 101 | Computer Science & Engineering | DBMS | B_001 | 201 |
| 101 | Computer Science & Engineering | Computer Networks | B_001 | 202 |
| 102 | Electronics & Communication Engineering | VLSI Technology | B_003 | 401 |
| 102 | Electronics & Communication Engineering | Mobile Communication | B_003 | 402 |
Question 1
What are the candidate keys of the original table?
(d) {Stu_ID, Stu_Course}
Question 2
Why is the table not in BCNF?
(c) Neither Stu_ID nor Stu_Course is a superkey.
6. R(A,B,C,D) is a relation. Which of the following does not have a lossless join, dependency preserving BCNF decomposition?
(c) AB->C, C->AD
7. Let R (A, B, C, D) be a relational schema with the following functional dependencies:
A → B, B → C,
C → D and D → B.
The decomposition of R into
(A, B), (B, C), (B, D)
(a) gives a lossless join, and is dependency preserving
8. R is decomposed or divided into R1 with FD { f1 } and R2 with { f2 }, then the decomposition is dependency preserving when
(a) f1 U f2 = F
9. Which of the following is NOT a rule for BCNF?
(c) All attributes should be atomic.
10. Consider the relation R (X,Y,Z,W) and the set F = {X -> Y, W -> Z}.
R is decomposed into R1(X,Y) and R2(Z,W).
Which of the following is true about R?
(b) Dependency preserving but not lossless join