MCQOPTIONS
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| 1. |
Let r be a relation instance with schema R = (A, B, C, D). We define r1 = ΠA, B, C (r) and r2 = ΠA.D (r). Let s = r1 * r2 where * denotes natural join. Given that the decomposition of r into r1 and r2 is lossy, which one of the following is TRUE? |
| A. | s ⊂ r |
| B. | r ∪ s |
| C. | r ⊂ s |
| D. | r * s = s |
| Answer» D. r * s = s | |