With respect to relational algebra, which of the following operations are…
2019
With respect to relational algebra, which of the following operations are included from mathematical set theory?
(a) Join
(b) Intersection
(c) Cartisian product
(d) Project
- A.
(a) and (d)
- B.
(b) and (c)
- C.
(c) and (d)
- D.
(b) and (d)
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Correct answer: B
Answer: Intersection and Cartesian product are included from mathematical set theory.
Why:
Intersection is a set operation that returns elements (tuples) common to both relations.
Cartesian product is the set-theoretic product of two relations, pairing every tuple of the first with every tuple of the second.
Projection (Project) is a relational operation that selects columns and is not a primitive set-theoretic operation.
Join is typically implemented using Cartesian product followed by selection; it is a derived relational operation rather than a basic set-theoretic primitive.
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