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Que. Given two relations R1(A, B) and R2(C, D), the result of following query
Select distinct A, B from R1, R2
is guaranteed to be same as R1 provided one of the following condition is satisfied.
a. R1 has no duplicates and R2 is empty.
b. R1 has no duplicates and R2 is non - empty.
c. Both R1 and R2 have no duplicates.
d. R2 has no duplicates and R1 is non - empty.
Answer:R1 has no duplicates and R2 is non - empty.
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