Let R(A, B, C, D, E, F) be a relational schema with the functional dependencies C → F, E → A, EC → D, A → B. Which of the following is a key for R?
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Correct answer: B. EC
Explanation
C and E never appear on a right side. (EC)⁺ = {E, C, F, A, D, B}, all attributes, so EC is the key.More Database Management Systems questions
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