Database Systems MCQ

 Q.1 Which of the following relational algebraic operations is not from set theory?

(A) Union

(B) Intersection

(C) Cartesian Product

(D) Select

Ans: (D)

 

Q.2 Which of the following ensures the atomicity of the transaction?

(A) Transaction management component of DBMS

(B) Application Programmer

(C) Concurrency control component of DBMS

(D) Recovery management component of DBMS

Ans: (A)

 

Q.3 If both the functional dependencies : X->Y and Y->X hold for two attributes X and Y then the relationship between X and Y is

(A) M:N

(B) M:1

(C) 1:1

(D) 1:M

Ans: (C)

 

Q.4 What will be the number of columns and rows respectively obtained for the operation, AB, if A B are Base union compatible and all the rows of a are common to B? Assume A has 4 columns and 10 rows; and B has 4 columns and 15 rows

(A) 4,0

(B) 0,0

(C) 4,5

(D) 8,5

Ans: (A)

 

Q.5 For correct behaviour during recovery, undo and redo operation must be

(A) Commutative

(B) Associative

(C) idempotent

(D) distributive

Ans: (C)

 

Q.6 Which of the following is not a consequence of non-normalized database?

(A) Update Anomaly

(B) Insertion Anomaly

(C) Redundancy

(D) Lost update problem

Ans: (D)

 

Q.7 Which of the following is true for relational calculus?

(A) "x(P(x))º¬($x)(¬P(x)) 

(B) "x(P(x))º¬($x)(P(x))

(C) "x(P(x))º($x)(¬P(x)) 

(D) "x(P(x))º($x)(P(x))

Ans: (A)

Q.8 The part of a database management system which ensures that the data remains in a consistent state is

(A) authorization and integrity manager

(B) buffer manager

(C) transaction manager

(D) file manager

Ans: (C)

 

Q.9 Relationships among relationships can be represented in an-E-R model using

(A) Aggregation

(B) Association

(C) Weak entity sets

(D) Weak relationship sets

Ans: (A)

 

Q.10 In tuple relational calculus P1 AND P2 is equivalent to

(A) (¬P1OR¬P2).

(B) ¬(P1OR¬P2).

(C) ¬(¬P1OR P2).

(D) ¬(¬P1OR ¬P2).

Ans: (D)

 

Q.11 If α->β holds then so does

(A) ϒα->ϒβ

(B) α->ϒβ

(C) both (A) and (B)

(D) None of the above

Ans: (A)

 

Q.12 Cascading rollback is avoided in all protocol except

(A) strict two-phase locking protocol.

(B) tree locking protocol

(C) two-phase locking protocol

(D) validation based protocol.

Ans: (D)

 

Q.13 Wait-for graph is used for

(A) detecting view serializability.

(B) detecting conflict serializability.

(C) deadlock prevention

(D) deadlock detection

Ans: (D)

 

Q.14 The expression sq1(E1 |X|q2E2) is the same as

(A) E1 |X|q1^ q2E2 (B) sq1 E1^sq2 E2

(C) E1 |X|q1ᵥ q2E2 (D) None of the above

Ans: (A)

 

Q.15 The clause alter table in SQL can be used to

(A) add an attribute

(B) delete an attribute

(C) alter the default values of an attribute

(D) all of the above

Ans: (D)

 

Q. 16 The data models defined by ANSI/SPARC architecture are

(A) Conceptual, physical and internal

(B) Conceptual, view and external

(C) Logical, physical and internal

(D) Logical, physical and view

Ans: (D)

 

Q.17 Whenever two independent one-to-many relationships are mixed in the same relation, a _______ arises.

(A) Functional dependency

(B) Multi-valued dependency

(C) Transitive dependency

(D) Partial dependency

Ans:(B)

 

Q.18 A table can have only one

(A) Secondary key

(B) Alternate key

(C) Unique key

(D) Primary key

Ans: (D)

 

Q.19 Dependency preservation is not guaranteed in

(A) BCNF

(B) 3NF

(C) PJNF

(D) DKNF

Ans: (A)

 

Q.20 Which is the best file organization when data is frequently added or deleted from a file?

(A) Sequential

(B) Direct

(C) Index sequential

(D) None of the above

Ans: (B)

 

Q.21 Which of the following constitutes a basic set of operations for manipulating relational data?

(A) Predicate calculus

(B) Relational calculus

(C) Relational algebra

(D) SQL

Ans: (C)

 

Q.22 An advantage of views is

(A) Data security

(B) Derived columns

(C) Hiding of complex queries

(D) All of the above

Ans: (A)

 

Q.23 Which of the following is not a recovery technique?

(A) Deferred update

(B) Immediate update

(C) Two-phase commit

(D) Shadow paging

Ans: (C)

 

Q.24 Isolation of the transactions is ensured by

(A) Transaction management

(B) Application programmer

(C) Concurrency control

(D) Recovery management

Ans: (C)

 

Q.25 _______ operator is used to compare a value to a list of literals values that have been specified.

(A) Like

(B) COMPARE

(C) BETWEEN

(D) IN

Ans: (A)