Directions (Q96–100): Consider the relations X(S, Si, C) and Y(S, P, D):
| X | ||
|---|---|---|
| S | Si | C |
| J | 1 | M |
| B | 2 | N |
| R | 3 | H |
| T | 4 | G |
| Y | ||
|---|---|---|
| S | P | D |
| J | S1 | CA |
| B | P1 | AB |
| R | D1 | DC |
| A | H1 | MD |
Find the number of tuples obtained by applying the operation X ⟕X.S = Y.S Y (left outer join).
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Correct answer: C. 4
Explanation
J, B and R match; T has no partner in Y and is kept with NULLs. Result: 4 tuples.More Database Management Systems questions
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