Directions (Q96–100): Relations X(S, Si, C) with tuples (J, 1, M), (B, 2, N), (R, 3, H), (T, 4, G), and Y(S, P, D) with tuples (J, S1, CA), (B, P1, AB), (R, D1, DC), (A, H1, MD).
Find the number of tuples obtained by applying the right outer join X ⟖ (X.S = Y.S) Y.
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Correct answer: C. 4
Explanation
J, B and R match in both relations (3 tuples). A right outer join also keeps Y's unmatched tuple A, padded with NULLs: 4 tuples.
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