NTA UGC NET JUNE 2023 Paper-1
January 30, 2024Question 6671 – Closure-Property
January 30, 2024GATE 1990
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Question 10
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Choose the correct alternatives (More than one may be correct).
Indicate which of the following statements are true:
A relational database which is in 3NF may still have undesirable data redundancy because there may exist:
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Transitive functional dependencies.
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Non-trivial functional dependencies involving prime attributes on the right-side.
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Non-trivial functional dependencies involving prime attributes only on the left-side.
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Non-trivial functional dependencies involving only prime attributes.
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Both (B) and (D).
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Question 10 Explanation:
A) Transitive functional dependency, so not in 3NF.
B) 3NF because right side is prime attribute.
C) Not in 3NF, because lets suppose ABC is a candidate key. Now consider
AB → Non-prime attribute
which show it is not in 3NF
D) Involves only prime attribute, so right side should definitely contain only prime attribute. So in 3NF.
B) 3NF because right side is prime attribute.
C) Not in 3NF, because lets suppose ABC is a candidate key. Now consider
AB → Non-prime attribute
which show it is not in 3NF
D) Involves only prime attribute, so right side should definitely contain only prime attribute. So in 3NF.
Correct Answer: E
Question 10 Explanation:
A) Transitive functional dependency, so not in 3NF.
B) 3NF because right side is prime attribute.
C) Not in 3NF, because lets suppose ABC is a candidate key. Now consider
AB → Non-prime attribute
which show it is not in 3NF
D) Involves only prime attribute, so right side should definitely contain only prime attribute. So in 3NF.
B) 3NF because right side is prime attribute.
C) Not in 3NF, because lets suppose ABC is a candidate key. Now consider
AB → Non-prime attribute
which show it is not in 3NF
D) Involves only prime attribute, so right side should definitely contain only prime attribute. So in 3NF.