Database-Management-System

Question 395

Consider the relation R shown in the below Figure.

X Y Z

X1 Y1 Z1

X1 Y1 Z2

X2 Y1 Z1

X2 Y1 Z3

List all the functional dependencies that this relation instance satisfies.

A	R: Z → Y, X → Y, and X → Z
B	R: Z →Y, X → Y, and XZ → Y
C	R: X →Y, X → Z, and XZ → Y
D	R: Z →Y, X → Z, and XZ → Y

Database-Management-SystemFunctional-DependencyAPPSC-2016-DL-CS

Question 395 Explanation:

option 1 is wrong bacause X → Z does not satisfy, since X1 is mapped to two values Z1 and Z2.
Option 3 is wrong because of X → Z.
Option 4 is wrong because of X → Z

Correct Answer: B

Question 395 Explanation:

option 1 is wrong bacause X → Z does not satisfy, since X1 is mapped to two values Z1 and Z2.
Option 3 is wrong because of X → Z.
Option 4 is wrong because of X → Z