Consider the relation R(P, Q, R, S, T, U, V, W, X, Y) and FDs: {P, Q, S} → T, R → Y, {P, Q} → V, {R, X} → X, Q → U, V → {W, X}. Which of the following is a candidate key?
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Correct answer: A. {P, Q, R, S}
Explanation
P, Q, R, S never appear on a right side, so they must be in every key. {P, Q, R, S}⁺ = P, Q, R, S, T, Y, V, U, W, X, i.e. all attributes. It is the candidate key.More Database Management Systems questions
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