Relational Algebra Quiz

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

• Relational

• Structural

• Procedural

• Fundamental

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

• Set intersection

• Natural join

• Assignment

• None of the mentioned

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

• Pi (Greek)

• Sigma (Greek)

• Lambda (Greek)

• Omega (Greek)

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

• Predicates, relation

• Relation, Predicates

• Operation, Predicates

• Relation, Operation

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

• Union

• Set-difference

• Difference

• Intersection

Which is a unary operation:

• Selection operation

• Primitive operation

• Projection operation

• Generalized selection

In precedence of set operators, the expression is evaluated from

• Left to left

• Left to right

• Right to left

• From user specification

Find the ID, name, dept name, salary for instructors whose salary is greater than $80,000 .

• {t | t ε instructor ∧ t[salary] > 80000}

• Э t ∈ r (Q(t))

• {t | Э s ε instructor (t[ID] = s[ID]∧ s[salary] > 80000)}

• None of the mentioned

“Find all students who have taken all courses offered in the Biology department.” The expressions that matches this sentence is :

• Э t ε r (Q(t))

• ∀ t ε r (Q(t))

• ¬ t ε r (Q(t))

• ~ t ε r (Q(t))

Which of the following is the comparison operator in tuple relational calculus

• ⇒

• =

• ε

• All of the mentioned