Relational Algebra Questions and Answers

1. Relational Algebra is a __________ query language that takes two relation as input and produces another relation as output of the query.

A. Relational
B. Structural
C. Procedural
D. Fundamental

Answer & Explanation

Answer: Option C

Explanation:

Procedural

This language has fundamental and other operations which are used on relations .

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2. Which of the following is a fundamental operation in relational algebra ?

A. Set intersection
B. Natural join
C. Assignment
D. None of the mentioned

Answer & Explanation

Answer: Option D

Explanation:

None of the mentioned

The fundamental operations are select, project, union, set difference, Cartesian product, and rename.

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3. Which of the following is used to denote the selection operation in relational algebra ?

A. Pi (Greek)
B. Sigma (Greek)
C. Lambda (Greek)
D. Omega (Greek)

Answer & Explanation

Answer: Option B

Explanation:

Sigma (Greek)

The select operation selects tuples that satisfy a given predicate.

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4. For select operation the ________ appear in the subscript and the ___________ argument appears in the paranthesis after the sigma.

A. Predicates, relation
B. Relation, Predicates
C. Operation, Predicates
D. Relation, Operation

Answer & Explanation

Answer: Option A

Explanation:

Predicates, relation

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5. The ___________ operation, denoted by -, allows us to find tuples that are in one relation but are not in another.

A. Union
B. Set-difference
C. Difference
D. Intersection

Answer & Explanation

Answer: Option B

Explanation:

Set-difference

The expression r - s produces a relation containing those tuples in r but not in s.