GATE 2012 CS (CS1) – Question 12

Databases · Integrity Constraints and Normal Forms · 1 mark · Multiple choice

Which statement is true?

Every 3NF relation is in BCNF.
A relation is in 3NF if every nonprime attribute is fully dependent on every key.
Every BCNF relation is in 3NF.
No relation is in both BCNF and 3NF.

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Show answer and explanation

Correct answer: (C) Every BCNF relation is in 3NF.

Explanation

BCNF requires every determinant of a nontrivial functional dependency to be a superkey. 3NF allows that condition or a prime right-side attribute, making it weaker. Hence every BCNF relation is 3NF, C. Fully depending on entire keys alone describes the 2NF condition, not all of 3NF.

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