Database-Management-System
August 29, 2024Database-Management-System
August 29, 2024Functional-Dependency
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Question 26
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Comprehension:
Answer question (96-100) based on the problem statement given below:
An organization needs to maintain database having five attributes A, B, C, D, E. These attributes are functionally dependent on each other for which functionally dependency set F is given as : F: {A→ BC, D → E, BC → D, A →D}. Consider a universal relation R(A, B, C, D, E) with functional dependency set F. Also all attributes are simple and take atomic values only.
→ Identify primary key of table R with functional dependency set F
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BC
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AD
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A
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AB
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Question 26 Explanation:
Since “A” is not in RHS of any FD so “A” is the key of relation R. NOw to see whether “A” is the primary key of “R” or not find its closure.
A+ = { A,B,C,D,E}. Hence A is the primary key of relation R
A+ = { A,B,C,D,E}. Hence A is the primary key of relation R
Correct Answer: C
Question 26 Explanation:
Since “A” is not in RHS of any FD so “A” is the key of relation R. NOw to see whether “A” is the primary key of “R” or not find its closure.
A+ = { A,B,C,D,E}. Hence A is the primary key of relation R
A+ = { A,B,C,D,E}. Hence A is the primary key of relation R