This set of Database Multiple Choice Questions & Answers (MCQs) focuses on “Relational Algebra”.
1. Relational Algebra is a __________ query language that takes two relation as input and produces another relation as output of the query.
Explanation: This language has fundamental and other operations which are used on relations .
2. Which of the following is a fundamental operation in relational algebra ?
a) Set intersection
b) Natural join
d) None of the mentioned
Explanation: The fundamental operations are select, project, union, set difference, Cartesian product, and rename.
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)
Explanation: The select operation selects tuples that satisfy a given predicate.
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
5. The ___________ operation, denoted by −, allows us to find tuples that are in one relation but are not in another.
Explanation: The expression r − s produces a relation containing those tuples in r but not in s.
6. 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. Which is a join condition contains an equality operator:
8. 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. 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. The assignment operator is denoted by
Explanation: The result of the expression to the right of the ← is assigned to the relation variable on the left of the ←.
Sanfoundry Global Education & Learning Series – Database Management System.