Relational Algebra and Relational Calculus MCQs

Question 1

What is relational algebra?

o A) A language for database creation
o B) A procedural query language for relational databases
o C) A data modeling technique
o D) A type of normalization

Answer 1

A procedural query language for relational databases

Question 2

Which of the following is NOT a fundamental operation in relational algebra?

o A) SELECT
o B) PROJECT
o C) JOIN
o D) INSERT

Answer 2

INSERT

Question 3

What does the SELECT operation do in relational algebra?

o A) Chooses specific columns
o B) Chooses specific rows
o C) Combines two relations
o D) Divides relations

Answer 3

Chooses specific rows

Question 4

What does the PROJECT operation do?

o A) Combines two tables
o B) Filters rows based on a condition
o C) Selects specific columns from a table
o D) Sorts the result set

Answer 4

Selects specific columns from a table

Question 5

Which symbol represents the UNION operation in relational algebra?

o A) ∩
o B) ∪
o C) ∖
o D) ⊕

Answer 5

∪

Question 6

Which type of JOIN returns all rows from both relations?

o A) INNER JOIN
o B) LEFT JOIN
o C) FULL OUTER JOIN
o D) CROSS JOIN

Answer 6

FULL OUTER JOIN

Question 7

What is the purpose of the RENAME operation?

o A) To change the name of a relation
o B) To filter rows in a relation
o C) To sort the result
o D) To combine two relations

Answer 7

To change the name of a relation

Question 8

What does the INTERSECT operation do?

o A) Returns rows that are in both relations
o B) Returns rows unique to each relation
o C) Combines rows from two relations
o D) Sorts the results of two relations

Answer 8

Returns rows that are in both relations

Question 9

In relational calculus, what does the term “tuple” refer to?

o A) A database table
o B) A single row in a relation
o C) A column in a table
o D) A data type

Answer 9

A single row in a relation

Question 10

What does the term “domain” refer to in relational calculus?

o A) The set of all possible values for an attribute
o B) A specific row in a relation
o C) A type of relationship
o D) A database schema

Answer 10

The set of all possible values for an attribute

Question 11

Which of the following symbols represents the existential quantifier in relational

o A) ∀
o B) ∃
o C) ∈
o D) ⊆

Answer 11

∃

Question 12

What is the purpose of the universal quantifier in relational calculus?

o A) To specify that a condition holds for at least one tuple
o B) To specify that a condition holds for all tuples
o C) To filter specific rows
o D) To project columns

Answer 12

To specify that a condition holds for all tuples

Question 13

In tuple relational calculus, how is a query expressed?

o A) Using logical predicates
o B) Using algebraic expressions
o C) Using SQL syntax
o D) Using mathematical formulas

Answer 13

Using logical predicates

Question 14

Which operation can be used to combine two relations with the same attributes?

o A) UNION
o B) INTERSECT
o C) JOIN
o D) PROJECT

Answer 14

UNION

Question 15

What is the result of a CROSS JOIN?

o A) A combination of rows from two relations without conditions
o B) A filtered set of rows based on a condition
o C) A set of common rows from two relations
o D) None of the above

Answer 15

A combination of rows from two relations without conditions

Question 16

Which of the following statements about relational calculus is true?

o A) It is a procedural language.
o B) It is a declarative language.
o C) It uses SQL syntax.
o D) It cannot express complex queries.

Answer 16

It is a declarative language.

Question 17

What is the main advantage of relational algebra?

o A) It is easier to learn than SQL.
o B) It provides a clear procedural approach to queries.
o C) It can express complex queries.
o D) It is used for database design.

Answer 17

It provides a clear procedural approach to queries.

Question 18

In relational algebra, what does the term “set difference” refer to?

o A) The result of removing common rows from two relations
o B) The combination of two relations
o C) The intersection of two relations
o D) The filtering of specific rows

Answer 18

The result of removing common rows from two relations

Question 19

What type of queries can relational calculus express?

o A) Only simple queries
o B) Complex queries involving multiple relations
o C) Only updates and deletes
o D) None of the above

Answer 19

Complex queries involving multiple relations

Question 20

Which of the following is a valid tuple relational calculus expression?

o A) {t | t ∈ Student ∧ t.Age > 20}
o B) SELECT * FROM Student WHERE Age > 20
o C) Student ∪ Graduate
o D) ALL OF THE ABOVE

Answer 20

{t | t ∈ Student ∧ t.Age > 20}

Question 21

What does the term “result set” refer to in the context of relational algebra?

o A) The final output of a query
o B) A temporary table
o C) A set of rules for operations
o D) A representation of data types

Answer 21

The final output of a query

Question 22

Which of the following is NOT a characteristic of relational algebra?

o A) It is procedural.
o B) It uses mathematical symbols.
o C) It is non-procedural.
o D) It combines relations.

Answer 22

It is non-procedural.

Question 23

What is the main purpose of using the aggregate functions in relational algebra?

o A) To filter rows
o B) To perform calculations on a set of values
o C) To combine relations
o D) To project columns

Answer 23

To perform calculations on a set of values

Question 24

What is the significance of the ORDER BY clause in SQL?

o A) To filter results
o B) To sort the output of a query
o C) To combine relations
o D) To group results

Answer 24

To sort the output of a query

Question 25

Which of the following is an example of an aggregate function? ## Footnote o A) COUNT() o B) SUM() o C) AVG() o D) All of the above

Answer 25

All of the above

Question 26

In relational calculus, which of the following is true about the variables used? ## Footnote o A) They can only be constants. o B) They must be attributes. o C) They can represent tuples from a relation. o D) They cannot be used in expressions.

Answer 26

They can represent tuples from a relation.

Question 27

What is the difference between a LEFT JOIN and a RIGHT JOIN? ## Footnote o A) They return different sets of rows. o B) They are identical operations. o C) LEFT JOIN returns all rows from the left table and matched rows from the right. o D) RIGHT JOIN returns all rows from the left table and matched rows from the right.

Answer 27

LEFT JOIN returns all rows from the left table and matched rows from the right.

Question 28

Which operation is used to count the number of tuples in a relation? ## Footnote o A) COUNT o B) SUM o C) AVG o D) DISTINCT

Answer 28

COUNT

Question 29

What is a primary key? ## Footnote o A) A unique identifier for a table o B) An attribute that can be null o C) A key that links two tables o D) A composite of multiple attributes

Answer 29

A unique identifier for a table

Question 30

What is the main advantage of using relational algebra? ## Footnote o A) It is easier to learn than SQL. o B) It provides a clear procedural approach to queries. o C) It can express complex queries.

Answer 30

It provides a clear procedural approach to queries.

Question 31

What is the purpose of the GROUP BY clause in SQL? ## Footnote o A) To filter rows o B) To group rows that have the same values in specified columns o C) To sort the result set o D) To combine multiple tables

Answer 31

To group rows that have the same values in specified columns

Question 32

Which of the following is a property of the UNION operation? ## Footnote o A) It combines relations without removing duplicates. o B) It requires the same number of attributes in both relations. o C) It can only be performed on relations with different schemas. o D) It can include null values.

Answer 32

It requires the same number of attributes in both relations.

Question 33

What is the significance of using the DISTINCT keyword in SQL? ## Footnote o A) It sorts the results. o B) It removes duplicate rows from the result set. o C) It limits the number of rows returned. o D) It groups the results.

Answer 33

It removes duplicate rows from the result set.

Question 34

In relational algebra, what does the term "join" refer to? ## Footnote o A) Combining two relations based on a common attribute o B) Filtering rows from a relation o C) Projecting specific columns o D) Aggregating data

Answer 34

Combining two relations based on a common attribute

Question 35

What is a foreign key? ## Footnote o A) A primary key that references another table o B) A unique identifier in a table o C) An attribute that can be null o D) A composite key made of multiple attributes

Answer 35

A primary key that references another table

Question 36

What does a natural join do? ## Footnote o A) Combines two relations based on a common attribute o B) Combines two relations without duplicates o C) Filters rows based on a condition o D) Projects specific columns

Answer 36

Combines two relations based on a common attribute