DBMS Relational Algebra & Calculus Quiz 4

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 used to denote the selection operation in relational algebra?

• Pi

• Sigma

• Lambda

• Omega

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

• Division

• Intersection

Which is a join condition contains an equality operator:

• Equi Join

• Cartesian

• Natural

• Left

In precedence of set operators, the expression is evaluated from

• Left to Right

• Right to Left

• From user specification

• Left & Right both in parallel

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 these

A query in the tuple relational calculus is expressed as:

• {t | P() | t}

• {P(t) | t }

• {t | P(t)}

• All of these

Which of the following symbol is used in the place of except?

• ^

• v

• ¬

• *

“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))