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Database-Management-System
November 12, 2023
Question 4374 – Research Aptitude
November 13, 2023
Database-Management-System
November 12, 2023
Question 4374 – Research Aptitude
November 13, 2023

Database-Management-System

Question 43

Let R = (A, B, C, D, E, F) be a relation scheme with the following dependencies: C→F, E→A, EC→D, A→B. Which of the following is a key of R?

A
CD
B
EC
C
AE
D
AC
Question 43 Explanation: 
Let’s check closure for each option,
A) (CD)+ = cdf
Not a key.
B) (EC)+ = ecdabf
Yes, it is a key.
C) (AE)+ = aeb
Not a key.
D) (AC)+ = abcf
Not a key.
Correct Answer: B
Question 43 Explanation: 
Let’s check closure for each option,
A) (CD)+ = cdf
Not a key.
B) (EC)+ = ecdabf
Yes, it is a key.
C) (AE)+ = aeb
Not a key.
D) (AC)+ = abcf
Not a key.
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