GATE 2013 CS (CS1) – Question 65

Databases · Integrity Constraints and Normal Forms · 2 marks · Multiple choice

R(A,B,C,D,E,F,G,H) has atomic fields. Exactly the dependencies implied by F={CH→G,A→BC,B→CFH,E→A,F→EG} hold. What is the highest normal-form description among these choices?

1NF but not 2NF
2NF but not 3NF
3NF but not BCNF
BCNF

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Correct answer: (A) 1NF but not 2NF

Explanation

Atomic fields establish 1NF. Candidate keys are AD,BD,ED,FD, so C,G,H are nonprime. The dependency A→C makes nonprime C depend on a proper subset A of candidate key AD. This violates 2NF. Therefore the relation is in 1NF but not 2NF, A.

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