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WorksheetsRelational Algebra and Calculus
Total questions: 20
Worksheet time: 9mins
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))
Which of the following is the comparison operator in tuple relational calculus
⇒
=
ε
All of these
An expression in the domain relational calculus is of the form
{P(x1, x2, . . . , xn) | < x1, x2, . . . , xn >}
{x1, x2, . . . , xn | < x1, x2, . . . , xn >}
{x1, x2, . . . , xn | x1, x2, . . . , xn}
{< x1, x2, . . . , xn > | P(x1, x2, . . . , xn)}
In domain relational calculus “there exist” can be expressed as
(P1(x))
(P1(x)) Э x
V x (P1(x))
Э x (P1(x))
A set of possible data values is called
Attribute
Degree
Tuple
Domain
When we want to display records with attributes from many relations then we use:
SELECT operation
PROJECT operation
JOIN operation
PERFORM operation
Relational Calculus describes about
'How' to evaluate a query
'What' is to be retrieved
'When' to evaluate a query
'Not' to evaluate a query
SELECT operator works _____ wise whereas PROJECT operator works _______ wise.
Row, Column
Column, Row
Row, Row
Column, Column
In order to perform Union operation on two relations, both operand and relations must be
Union compatible
Set compatible
Difference compatible
User compatible
Relational Calculus is of ______ types
2
3
4
5
QBE stands for
Query By Example
Query By Entity
Question By Example
Question By Entity
