Engineering Questions with Answers - Multiple Choice Questions

# MCQs on Relational Algebra

1 - Question

Relational Algebra is a __________ query language that takes two relations as input and produces another relation as an output of the query.
a) Relational
b) Structural
c) Procedural
d) Fundamental

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

2 - Question

Which of the following is a fundamental operation in relational algebra?
a) Set intersection
b) Natural join
c) Assignment
d) None of the mentioned

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

3 - Question

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)

Explanation: The select operation selects tuples that satisfy a given predicate.

4 - Question

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

Explanation: None.

5 - Question

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

Explanation: The expression r − s produces a relation containing those tuples in r but not in s.

6 - Question

Which is a unary operation:
a) Selection operation
b) Primitive operation
c) Projection operation
d) Generalized selection

Explanation: Generalization Selection takes only one argument for operation.

7 - Question

Which is a join condition contains an equality operator:
a) Equijoins
b) Cartesian
c) Natural
d) Left

Explanation: None.

8 - Question

In precedence of set operators, the expression is evaluated from
a) Left to left
b) Left to right
c) Right to left
d) From user specification

Explanation: The expression is evaluated from left to right according to the precedence.

9 - Question

Which of the following is not outer join?
a) Left outer join
b) Right outer join
c) Full outer join
d) All of the mentioned

Explanation: The FULL OUTER JOIN keyword combines the result of both LEFT and RIGHT joins.

10 - Question

The assignment operator is denoted by
a) ->
b) <-
c) =
d) ==