Question 21Asked in UGC NET Computer Science, December 2014 (Paper II & III, Selected Questions)

The best normal form of relation scheme R(A, B, C, D) along with the set of functional dependencies F = { AB → C, AB → D, C → A, D →B} is :

ABoyce-Codd Normal form
BThird Normal form
CSecond Normal form
DFirst Normal form

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Correct answer: (B) Third Normal form

Explanation

The candidate keys are AB, CD, BC and AD, so A, B, C and D are all prime attributes and the relation is in 3NF. It is not in BCNF because in C → A and D → B the left side is not a superkey. Hence the best normal form is 3NF.

The best normal form of relation scheme R(A, B, C, D) along with the set of functional dependencies F = { AB → C, AB → D, C → A, D →B} is :

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