Database-Management-System
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Question 358
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Let R = (A, B, C, D, E, F) be a relation schema with the following dependencies:
C → F,E → A, EC → D, A → B
Which of the following is a key for R?
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CD
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EC
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AE
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AC
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Question 358 Explanation:
Let’s find closure of each options,
(CD)+ = CDF X
(EC)+ = ECFDAB ✓
(AE)+ = AEB X
(AC)+ = ACBF X
(CD)+ = CDF X
(EC)+ = ECFDAB ✓
(AE)+ = AEB X
(AC)+ = ACBF X
Correct Answer: B
Question 358 Explanation:
Let’s find closure of each options,
(CD)+ = CDF X
(EC)+ = ECFDAB ✓
(AE)+ = AEB X
(AC)+ = ACBF X
(CD)+ = CDF X
(EC)+ = ECFDAB ✓
(AE)+ = AEB X
(AC)+ = ACBF X
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