1
GATE CSE 2024 Set 1
MCQ (More than One Correct Answer)
+2
-0.66

The symbol → indicates functional dependency in the context of a relational database. Which of the following options is/are TRUE?

A

(X, Y) → (Z, W) implies X → (Z, W)

B

(X, Y) → (Z, W) implies (X, Y) → Z

C

((X, Y) → Z and W → Y) implies (X, W) → Z

D

(X → Y and Y → Z) implies X → Z

2
GATE CSE 2021 Set 1
+2
-0.67

Consider the relation R(P, Q, S, T, X, Y, Z, W) with the following functional dependencies.

PQ → X; P → YX; Q → Y; Y → ZW

Consider the decomposition of the relation R into the constituent relations according to the following two decomposition schemes.

D1 : R = [(P, Q, S, T); (P, T, X); (Q, Y); (Y, Z, W)]

D2 : R = [(P, Q, S); (T, X); (Q, Y); (Y, Z, W)]

Which one of the following options is correct?

A

D1 is a lossy decomposition, but D2 is a lossless decomposition.

B
Both D1 and D2 are lossless decompositions.
C
Both D1 and D2 are lossy decompositions.
D
D1 is a lossless decomposition, but D2 is a lossy decomposition.
3
GATE CSE 2020
+2
-0.67
Consider a relational table R that is in 3NF, but not in BCNF. Which one of the following statements is TRUE?
A
A cell in R holds a set instead of an atomic value.
B
R has a nontrivial functional dependency X $$\to$$ A, where X is not a superkey and A is a non-prime attribute and X is not a proper subset of any key
C
R has a nontrivial functional dependency X $$\to$$ A, where X is not a superkey and A is a non-prime attribute and X is a proper subset of some key.
D
R has a nontrivial functional dependency X $$\to$$ A, where X is not a superkey and A is a prime attribute.
4
GATE CSE 2019
+2
-0.67
Let the set of functional dependencies

F = {QR → S, R → P, S → Q}

hold on a relation schema X = (PQRS). X is not in BCNF. Suppose X is decomposed into two schemas Y and Z, where Y = (PR) and Z = (QRS).

Consider the two statements given below.

I. Both Y and Z are in BCNF
II. Decomposition of X into Y and Z is dependency preserving and lossless

Which of the above statements is/are correct?
A
I only
B
Neither I nor II
C
II only
D
Both I and II
GATE CSE Subjects
EXAM MAP
Medical
NEET