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DBMS Questions and Answers

DBMS Questions and Answers
DBMS questions
Database Questions
DBMS questions for competition exams


1 The concept of locking can be used to solve the problem of

 Lost update

 Uncommitted dependency

 Inconsistent data


(a) 1 and 4
(b) 2,3 and 4
(c)   1,2 and 3
(d)All 1,2,3 and 4 can be solved
answer- C

2 What are the potential problems when a DBMS executes multiple transactions concurrently?

The lost update problem

The dirty read problem

The unrepeatable read problem

 The phantom problem

(a)3 and 4 only
(b)1,2 and 4 only
(c)2 and 3 only
(d)All of 1,2,3 and 4


3  The data flow model of an application mainly shows

(a) The underlying data and the relationships among them

(b) Processing requirements and the flow of data

(c) Decision and control information

(d) Communication network structure


4  Which of the following desired features are beyond the capability of relational algebra?

(a) Aggregate computation

(b) Multiplication

(c) Finding transitive closure

(d) All of the above


5 Redundancy is dangerous as it is a potential threat to data

(a) Integrity

(b) Consistency

(c) Sufficiency

(d) Both (a) and (b) above


6 The employee salary should not be greater than Rs. 2000.This is

(a) Integrity constraint

(b) Referential constraint

(c) Over-defined constraint

(d) Feasible constraint


7 Manager’s salary details are hidden from the employee. This is

(a) Conceptual level data hiding

(b) Physical level data hiding

(c) External level data hiding

(d) None of the above


8 A trigger is

(a) A statement that enables to start any DBMS

(b) A statement that is executed by the user when debugging an application program

(c) A condition the system tests for the validity of the database user

(d) A statement that is executed automatically by the system as a side effect of a modification to the database


9 Controlling redundancy in a database management system helps to

(a) Avoid duplication of effort

(b) Avoid unnecessary wastage of storage space

(c) Avoid inconsistence among data.

(d) All of the above


The database environment has all of the following components except

(a) Users

(b) Separate files

(c) Database

(d) Database administration


11 The way a particular application views the data from the database that the application uses is a

(a) Module

(b) Relational

(c) Schema

(d) Subschema


12 A data dictionary doesn’t provide information about

(a) Where data is located

(b) The size of the disk storage disk

(c) Who owns or is responsible for the data

(d) How the data is used


13 what does the data dictionary identify?

(a) Field names

(b) Field types

(c) Field formates

(d) all of the above


14 which of the following best describes the internal level of the ANSI/SPARC three level architecture?

(a) The internal level is concerned with the layout of records and their locations within disk blocks.

(b) The internal level is concerned with the data as seen by individuals internal to the enterprise.

(c) The internal level is concerned with the users view of the data.

(d) The internal level provides a conceptual view of the data structure.


15 Select the correct statement from the following on referential integrity.

(a) Referential integrity constraints check whether the primary key values are unique.

(b) Referential integrity constraints are specified between two relations in a schema.

(c) Referential integrity constraints check whether an attribute value lies in the given range.

(d) Referential integrity constraints are specified between entities having recursive relationships.


16 Consider the following statements.

(a) An entity integrity constraint states that no primary key value can be null.

(b) A referential integrity constraint is specified between two relations.

(c) A foreign key cannot be used to refer to its own relation. Identify which of the above statements is /are correct?

(1) Only 1

(2) Only 2

(3) Only 2 and 3

(4) Only 1 and 2


17 Which of the following operations is not part of the five basic set operations in relational algebra?

(a) Union

(b) Division

(c) Cartesian Product

(d) Set Difference


18 Which of the following relational algebraic operation is not a commutative operation?

(a) Union

(b) Intersection

(c) Selection

(d) Projection


19 If a system can enforce referential integrity, then this ensures that

(a) A record can never contain a null value for a foreign key attribute.

(b) A non-null foreign key attribute always refers to another record

(c) A foreign key attributes in a record always refers to another record which contains nulls

(d) A foreign key attribute in a record always refers to another record which does not contain nulls


20 3NF is preferred than BCNF because

(a) We normally choose to retain dependency preservation

(b) A high penalty in system performance is to be paid or risk the integrity of the data in our database.

(c) There isn’t any problem of repletion of information

(d) Given statement is wrong.

(1) Only 4 is true

(2) Only 2 and 3 are true

(3) Only 1 and 2 are true

(4) Only 3 is true


21 Which of the following is generally a benefit of normalization?

(a) Performance is improved

(b) Insertion anomalies are avoided

(c) Selection anomalies are avoided

(d) Number of tables is reduced


22 Which of the following is updatable?

(a) View with a single defining table if view at tributes contains the primary key or some other candidate key of the base relation.

(b) View defined on multiple tables using joins

(c) View defined using grouping and aggregate functions

(d) All of the above


23 Constraints are specified as a part of

(a) Data definition

(b) Data manipulation

(c) Data control

(d) None of the above


24 Which of the following cannot be restarted?

(a) Transaction aborted due to software error.

(b) Transaction aborted due to hardware error.

(c) Transaction aborted due to hardware or software error that was created by internal logic.

(d) Observable external writes.


25 Locking was introduced into database so that

(a) Keys can be provided to maintain security.

(b) All simultaneous transactions are prevented.

(c) Passwords can be provided to maintain security.

(d) Consistency can be enforced.


26 Which level of locking provides the highest degree of concurrency flight in a relational database?

(a) Page

(b) Table

(c) Row

(d) Page, table, and roe level locking allow the same degree of concurrency


27 which of the following is true for two-phase locking?

(a) Lock acquisition is the second phase

(b) Locks can be acquired at any time

(c) Locks are acquired in the first phase

(d) None of the above


28 Which of the following is not a file operation?

(a) Find Next

(b) Find

(c) Reset

(d) None of the above


29 Index sequential file is made of all of these expect

(a) Primary data storage area

(b) Overflow area

(c) Hierarchy of indices

(d) Address of prime data track


30 Relations produced from an ER model will always be in 

(a)First normal form

(b) Second normal form

(c) Third normal form

(d) Fourth normal form


31 A primary key if combined with a foreign key creates

(a) Parent child relationship between the tables that connect them

(b) Many to-many relationship between the tables that connect them

(c) Network model between the tables that connect them

(d) None of the above


32 What is the goal of concurrency control protocol?

(a)Schedule should be serializable

(b) Schedule should be recoverable

(c) Both (a) and (b)

(d) None of these


33 A given relation is known to be in third normal form. Select the statement which can be inferred from this.

(a) All attributes contribute to the primary key

(b) Each non key attribute determine the primary key

(c) Each non-key attribute is determine by the primary key

(d) Every determinant is a candidate key


34 Display all the information for everyone in the EMPLOYEE who is a clerk.

(a) SELECT*FROM employee

(b) SELECT*FROM employee. WHERE title =’-‘;

(c) SELECT*FROM employee WHERE title =’clerk’;

(d) None of the above


35 If the precedency graph of a given schedule is acyclic, then schedule- 

(a)Will be always serializable

(b) Will never serializable

(c) May be serializable

(d) Can’t say


36 When n transactions are run concurrently and in an interleaved manner, the number of possible schedules are

(a) Much larger than n!

(b) Much lower than n!

(c) Much larger than (n-1)!

(d) Much lower than (n-1)!


37 Which allocation scheme would work best for a file system implemented on a device that can only be accessed sequentially, a tape drive, for instance?

(a) Contiguous allocation

(b) Non contiguous allocation

(c) Indexed allocation

(d) None of the above


38 Which of the following is correct?

(a) B trees are for storing data on disk and B+ trees are for main memory.

(b) Range queries are faster on B+ trees.

(c) B trees are for primary indexes and B+ trees are for secondary indexes.

(d) The height of B+ tree is independent of the number of records.


39 A B tree used as an index for a large database table has four levels including the root node. If a new key is inserted in this index, then the maximum number of nodes that could be newly created in the process are

(a) 5

(b) 4

(c) 3

(d) 2


40 With respect to the B+ tree index method, select the true statements

(a) Records are physically stored in primary key order.

(b) B+ trees use a hashing algorithm.

(c) The index tree may become unbalanced as a result of updates.

(d) None of the above


41 Which is the best suitable for sequential access of data

(a) B tree

(b) B+ tree

(c) Both

(d) None of the above


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