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Question 54Asked in UGC NET Computer Science, June 2014 (Paper II & III, Selected Questions)

Consider the schema R = {S, T, U, V} and the dependencies S → T, T → U, U → V and V → S. If R = (R₁ and R₂) be a decomposition such that R₁ ∩ R₂ = φ then…

Consider the schema R = {S, T, U, V} and the dependencies S → T, T → U, U → V and V → S. If R = (R₁ and R₂) be a decomposition such that R₁ ∩ R₂ = φ then the decomposition is
  1. ANot in 2 NF
  2. BIn 2 NF but not in 3 NF
  3. CIn 3 NF but not in 2 NF
  4. DIn both 2 NF and 3 NF
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Correct answer: (D) In both 2 NF and 3 NF

Explanation

R₁ ∩ R₂ ≠ φ. This makes the decomposition lossless join, as all the attributes are keys, R₁ ∩ R₂ will be a key of the decomposed relation Now, even the original relation R is in 3NF (Even BCNF) as all the attributes are prime attributes (in fact attribute is a candidate key) Hence, any decomposition will also be in 3NF and 2NF, So the answer is option (d).

From UGC NET Computer Science PYQ, June 2014 (Paper II & III, Selected Questions)

This is question 54 of UGC NET Computer Science PYQ, June 2014 (Paper II & III, Selected Questions). See all questions of this paper with answers, or attempt the paper as a timed online test to get your score and all-India rank.