Relational Algebra MCQs

Q#1: Relational algebra is a:
(A) Procedural query language
(B) Non-procedural query language
(C) Programming language
(D) Data model
Answer: (A) Procedural query language

Q#2: Which of the following is a unary operation in relational algebra?
(A) Union
(B) Join
(C) Selection
(D) Cartesian Product
Answer: (C) Selection

Q#3: Selection operation is denoted by:
(A) π
(B) σ
(C) ⋈
(D) ∪
Answer: (B) σ

Q#4: Projection operation is denoted by:
(A) π
(B) σ
(C) ∩
(D) −
Answer: (A) π

Q#5: Projection operation is used to select:
(A) Rows
(B) Columns
(C) Tables
(D) Keys
Answer: (B) Columns

Q#6: Selection operation is used to select:
(A) Columns
(B) Attributes
(C) Rows
(D) Domains
Answer: (C) Rows

Q#7: Union operation requires relations to be:
(A) Of different degree
(B) Union compatible
(C) Without keys
(D) Empty
Answer: (B) Union compatible

Q#8: Intersection operation returns:
(A) All tuples
(B) Common tuples
(C) Unique columns
(D) Duplicate rows
Answer: (B) Common tuples

Q#9: Set difference operation is denoted by:
(A) −
(B) ∪
(C) ∩
(D) ×
Answer: (A) −

Q#10: Cartesian product is denoted by:
(A) ∪
(B) ×
(C) −
(D) π
Answer: (B) ×

Q#11: Join operation combines relations based on:
(A) Common attributes
(B) Number of rows
(C) Domain
(D) Keys only
Answer: (A) Common attributes

Q#12: Natural join is denoted by:
(A) ⋈
(B) ×
(C) ∪
(D) π
Answer: (A) ⋈

Q#13: Theta join is a join with:
(A) Equality condition only
(B) Any comparison condition
(C) No condition
(D) Multiple tables only
Answer: (B) Any comparison condition

Q#14: Equi-join is based on:
(A) > condition
(B) < condition
(C) = condition
(D) ≠ condition
Answer: (C) = condition

Q#15: Division operation is used to:
(A) Divide tables
(B) Handle queries with “for all” condition
(C) Remove duplicates
(D) Select columns
Answer: (B) Handle queries with “for all” condition

Q#16: Which operation is binary?
(A) Selection
(B) Projection
(C) Rename
(D) Union
Answer: (D) Union

Q#17: Rename operation is denoted by:
(A) ρ
(B) σ
(C) π
(D) ∪
Answer: (A) ρ

Q#18: Relational algebra operations result in:
(A) Scalar value
(B) Boolean value
(C) Relation
(D) Integer
Answer: (C) Relation

Q#19: Which of the following removes duplicate tuples?
(A) Selection
(B) Projection
(C) Join
(D) Cartesian product
Answer: (B) Projection

Q#20: Which operation increases the number of columns?
(A) Selection
(B) Projection
(C) Join
(D) Difference
Answer: (C) Join

Q#21: Which operation increases the number of rows?
(A) Cartesian product
(B) Projection
(C) Rename
(D) Selection
Answer: (A) Cartesian product

Q#22: Relational algebra is based on:
(A) Graph theory
(B) Set theory
(C) Tree structure
(D) File system
Answer: (B) Set theory

Q#23: Selection operation is equivalent to:
(A) WHERE clause
(B) SELECT clause
(C) FROM clause
(D) GROUP BY clause
Answer: (A) WHERE clause

Q#24: Projection operation is equivalent to:
(A) WHERE clause
(B) SELECT clause
(C) HAVING clause
(D) ORDER BY clause
Answer: (B) SELECT clause

Q#25: Which operation combines all tuples from two relations?
(A) Intersection
(B) Difference
(C) Union
(D) Selection
Answer: (C) Union

Q#26: The result of union operation will have:
(A) Duplicate tuples
(B) Only unique tuples
(C) Null values only
(D) Only common tuples
Answer: (B) Only unique tuples

Q#27: Which join does not require a condition?
(A) Theta join
(B) Equi-join
(C) Natural join
(D) Cartesian product
Answer: (D) Cartesian product

Q#28: The degree of relation after projection is:
(A) Increased
(B) Decreased or same
(C) Doubled
(D) Always same
Answer: (B) Decreased or same

Q#29: The cardinality of relation after selection is:
(A) Increased
(B) Decreased or same
(C) Always same
(D) Doubled
Answer: (B) Decreased or same

Q#30: Relational algebra is mainly used for:
(A) Database design
(B) Query processing
(C) Data encryption
(D) Hardware installation
Answer: (B) Query processing