DBMS MCQ Questions and Answer Set-4

1. Which of the following relational algebra operations do not require the participating tables to be union-compatible?

(A) ) Union

(B) Intersection

(C) Difference

(D) Join

Ans: (D)

2. Which of the following is not a property of transactions?

(A) Atomicity

(B) Concurrency

(C) Isolation

(D) Durability

Ans: (B)

3. Checkpoints are a part of

(A) Recovery measures.

(B) Security measures.

(C ) Concurrency measures.

(D) Authorization measures.

Ans: (A)

4. Tree structures are used to store data in

(A) Network model.

(B) Relational model.

(C) Hierarchical model.

(D) File-based system.

Ans: (C )

5. Precedence graphs help to find a

(A) Serializable schedule.

(B) Recoverable schedule.

(C) Deadlock free schedule.

(D) Cascades schedule.

Ans: (A)

6. It is an abstraction through which relationships are treated as higher-level entities

(A) Generalization.

(B) Specialization.

(C) Aggregation.

(D) Inheritance.

Ans: (C )

7. A relation is in ____________ if an attribute of a composite key is dependent on an attribute of another composite key.

(A) 2NF

(B) 3NF

(C) BCNF

(D) 1NF

Ans: (B)

8. What are the desirable properties of a decomposition?

(A) Partition constraint.

(B) Dependency preservation.

(C) Redundancy.

(D) Security.

Ans: (B)

9. In an E-R diagram double lines indicate

(A) Total participation.

(B) Multiple participation.

(C) Cardinality N.

(D) None of the above.

Ans: (A)

10. In SQL the statement select * from R, S is equivalent to

(A) Select * from R natural join S.

(B) Select * from R cross join S.

(C) Select * from R union join S.

(D) Select * from R inner join S.

Ans: (B)

11. Which of the following is not a consequence of concurrent operations?

(A) Lost update problem.

(B) Update anomaly.

(C) Unrepeatable read.

(D) Dirty read.

Ans: (B)

12. If the closure of an attribute set is the entire relation then the attribute set is a

(A) superkey

(B) candidate key

(C) primary key

(D) not a key

Ans: (A)

13. Which one is the correct statement?

Logical data independence provides the following without changing application programs:

(i) Changes in access methods.

(ii) Adding new entities in the database

(iii) Splitting an existing record into two or more records

(iv) Changing the storage medium

(A) (i) and (ii)

(B) (iv) only,

(C) (i) and (iv)

(D) (ii) and (iii)

Ans: (D)

14. Which of the following statement on the view concept in SQL is invalid?

(A) All views are not updateable

(B) The views may be referenced in an SQL statement whenever tables are

referenced.

(C) The views are instantiated at the time they are referenced and not when they

are defined.

(D) The definition of a view should not have a GROUP BY clause in it.

Ans: (D)

15.The Functional Dependencies A -> B , DB -> C implies

(A) DA -> C

(B) A -> C

(C) B -> A

(D) DB -> A

Ans: (A)

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