Given relations r(w, x) and s(y, z), the result of
SELECT DISTINCT w, x
FROM r, s is guaranteed to be same as r, provided
(A) r has no duplicates and s is non-empty
(B) r and s have no duplicates
(C) s has no duplicates and r is non-empty
(D) r and s have the same number of tuples
Answer: (A)
Explanation: See question 3 of https://www.geeksforgeeks.org/database-management-system-set-1/
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