Important MCQ of Database Concepts of Computer Science

Important MCQ of Database concept of Computer Science.

Important MCQ of Database Concepts of Computer Science is very important unit. Here we will discuss some important MCQ questions related to Database concepts. These Questions are very important for CUET UG Computer Science Exam for class 12 students and also for various other competitive exams such as SSC , Haryana CET , UPSC CSE , Bank exams etc.

Important MCQ of Database Concepts of Computer Science: Syllabus for Unit 2 of Database Concepts of Computer Science is:

Introduction to database concepts, difference between database and file system, relational data model: concept of domain, tuple, relation, keys – candidate key, primary key, alternate key, foreign key; Relational algebra: selection, projection, union, set difference and cartesian product;

Here are some MCQs for Database Concepts of Computer Science:

Ques 1: Data is a collection of _________ facts which have not been processed to reveal useful information.

a. Raw

b. Facts

c. Process

d. None of the above

Answer: a. Raw

Ques 2: What are the benefits of databases ____________.

a. Data Redundancy

b. Data Inconsistency

c. Lack of Data Integration

d. All of the above

Answer: d. All of the above

Ques 3: Which of the following is not a valid SQL type?

a. Float

b. Numeric

c. Decimal

d. Character

Answer: d. Character

Ques 4. Which of the following is not a DDL command?

a. Truncate

b. Alter

c. Create

d. Update

Answer: d. Update

Ques 5: Any change in the structure of data would be done in the catalog and hence programs which access this data need not be modified. This property is called __________.

a. Program – Data Independence

b. Self describing

c. Sharing of data

d. None of the above

Answer: a. Program – Data Independence

Ques 6: Users who use the database for querying , modifying and generating reports as per their needs. They are not concerned about the working and designing of the database known as _________.

a. End users

b. Database Administrator

c. Application programmers

d. All of the above

Answer: a. End users

Ques 7: Limitation of using DBMS approach_______

a. High cost

b. Security and recovery overheads

c. Both a) and b)

d. None of the above

Answer: c. Both a) and b)

Ques 8 What is a database?

a) Organized collection of information that cannot be accessed, updated, and managed
b) Collection of data or information without organizing
c) Organized collection of data or information that can be accessed, updated, and managed
d) Organized collection of data that cannot be updated

Answer: Answer: c
Explanation: It is defined as an organized collection of data or information for easy access, updating, and management in a computer.

Ques 9. 4. Who created the first DBMS?
a) Edgar Frank Codd
b) Charles Bachman
c) Charles Babbage
d) Sharon B. Codd

Answer: Answer: b
Explanation: Charles Bachman along with his team invented the first DBMS known as Integrated Data Store (IDS).

Ques 10. Which of the following is known as a set of entities of the same type that share same properties, or attributes?
a) Relation set
b) Tuples
c) Entity set
d) Entity Relation model

Answer: c
Explanation: In the actual world, an entity is a distinct “thing” or “object” from all other objects. For example: Each employee of an organization is an entity.

 Ques 11.The values appearing in given attributes of any tuple in the referencing relation must likewise occur in specified attributes of at least one tuple in the referenced relation, according to _____________________ integrity constraint.
a) Referential
b) Primary
c) Referencing
d) Specific

Answer: a
Explanation: Consider 2 relations r1 and r2. r1 may include among its attributes the primary key of relation r2. This attribute is called a foreign key from r1, referencing r2. The relation r1 is also called the referencing relation of the foreign key dependency, and r2 is called the referenced relation of the foreign key.

Ques 12. _____________ is a hardware component that is most important for the operation of a database management system.
a) Microphone
b) High speed, large capacity disk to store data
c) High-resolution video display
d) Printer

Answer: b
Explanation: Since all the data are stored in form of memory in the disk, a high speed, and large-capacity disk is required for the operation of the database management system.

 Ques 13. The ability to query data, as well as insert, delete, and alter tuples, is offered by ____________
a) TCL (Transaction Control Language)
b) DCL (Data Control Language)
c) DDL (Data Definition Langauge)
d) DML (Data Manipulation Langauge)

Answer: d
Explanation: A query is a request for data or information. Relational Schema is the design and structure of the relation. DDL consists of commands that help in modifying. DML performs the change in the values of the relation.

Ques 14  ______________ is a set of one or more attributes taken collectively to uniquely identify a record.
a) Primary Key
b) Foreign key
c) Super key
d) Candidate key

Answer: c
Explanation: Foreign key creates a relationship between two relations. Super key is the superset of all the keys in a relation. A candidate key is used to identify tuples in a relation.

Ques 15. Which command is used to remove a relation from an SQL?
a) Drop table
b) Delete
c) Purge
d) Remove

Answer: a
Explanation: Delete command is used to delete the existing record from the table. The drop table deletes the whole structure of the relation. Purge removes the table which cannot be obtained again.

Ques 16. Which of the following set should be associated with weak entity set for weak entity to be meaningful?
a) Neighbour set
b) Strong entity set
c) Owner set
d) Identifying set

Answer: d
Explanation: Every weak entity must be linked to an identifying entity; in other words, the existence of the weak entity set is contingent on the presence of the identifying entity set. The weak entity set that the identifying entity set identifies is said to be owned by the identifying entity set. Owner entity set is another name for it.

Ques 17. Which of the following is generally used for performing tasks like creating the structure of the relations, deleting relation?

1. DML(Data Manipulation Language)
2. Query
3. Relational Schema
4. DDL(Data Definition Language)

Answer: D

Explanation: The term “DDL” stands for Data Definition Language, used to perform all other essential tasks such as deleting relation and related schemas in defining the structure relation.

Ques 18. Which of the following provides the ability to query information from the database and insert tuples into, delete tuples from, and modify tuples in the database?

1. DML(Data Manipulation Language)
2. DDL(Data Definition Language)
3. Query
4. Relational Schema

Answer: A

Explanation: The term “DML” stands for the Data Manipulation Language used to perform the required changes in the relation’s values.

Ques 19. Which one of the following given statements possibly contains the error?

1. select * from emp where empid = 10003;
2. select empid from emp where empid = 10006;
3. select empid from emp;
4. select empid where empid = 1009 and Lastname = ‘GELLER’;

Answer: D

Explanation: The Query given in option D does not contain the “from” clause, which specifies the relation from which the values have to be selected or fetched. Therefore the correct answer is D.

Ques 20. A Database Management System is a type of _________software.

1. It is a type of system software
2. It is a kind of application software
3. It is a kind of general software
4. Both A and C

Answer: A

Explanation: The DBMS (or Database Management System) is a kind of system software used for several operations such as creating tables/databases, storing data, managing databases. It also allows modifying the data stored in the database as well.

Ques 21. The term “FAT” is stands for_____

1. File Allocation Tree
2. File Allocation Table
3. File Allocation Graph
4. All of the above

Answer: B

Explanation: The term “FAT” can be described as a file structure (or file architecture). In which all the information about the files where they are stored and where all these files need to be stored or in which directory, all that information generally stored in the file structure. Therefore the Operating system creates a table in which all the files and clusters are stored, known as the file allocation table.

Ques 22.The term “NTFS” refers to which one of the following?

1. New Technology File System
2. New Tree File System
3. New Table type File System
4. Both A and C

Answer: A

Explanation: In the old operating systems, the file structure used to store and manage files is called the FAT 32 ( or File Allocation Table). Later, when the technology evolves with time, a new type of file system is introduced, known as the New Technology File System. It overcomes all the drawbacks, issues that exist in FAT file architecture and has many other new features such as it is fast, it can handle files whose size is even greater than 4 GB.

Ques 23. E-R model uses this symbol to represent weak entity set ?

• Dotted rectangle.
• Diamond
• Doubly outlined rectangle
• None of these

Answer: Doubly outlined rectangle

Ques 24. SET concept is used in :

• Network Model
• Hierarchical Model
• Relational Model
• None of these

Answer: Network Model

 Ques 25. Key to represent relationship between tables is called

• Primary key
• Secondary Key
• Foreign Key 
• None of these

Answer: Foreign Key 

Ques 26. _______ produces the relation that has attributes of R1 and R2

• Cartesian product 
• Difference
• Intersection
• Product

Answer: Cartesian product 

Ques 27. Which of the following is a Data Model?

a. entity-relationship model

b. relational data model

c. object-based data model

d. all of the above

Answer: all of the above

Ques 28. A characteristic of an entity.

a. Relation

b. Attribute

c. Parameter

d. Constraint

Answer» B. Attribute

Ques 29. A model developed by Hammer and Mc Leod in 1981.

a. SDM

b. OODBM

c. DDM

d. RDM

Answer» A. SDM

Ques 30. Object=_________+relationships.

a. data

b. attributes

c. entity

d. constraints

Answer» C. entity

Ques 31. Data Redundancy increases the cost of storing and retrieving data.

a. False

b. True

c. none

d. all

Answer: b. true

Ques.32 If in redundant file common fields are not matching then it results in _____________.

a. Data Inconsistency

b. Data Integrity Problem

c. Data Isolation

d. Data Redundancy

Ques 33. The function that an entity plays in a relationship is called that entity’s _____________

a. Participation

b. Position

c. Role

d. Instance

Answer : c. Role

Ques 34. _____________ can help us detect poor E-R design.

a. Database Design Process

b. E-R Design Process

c. Relational scheme

d. Functional dependencies

Answer: D. Functional dependencies

Ques 35. Which of the following has each related entity set has its own schema and there is an additional schema for the relationship set.

a. A many-to-many relationship set

b. A multivalued attribute of an entity set

c. A one-to-many relationship set

d. All of the mentioned

Answer: A. A many-to-many relationship set.

Ques 36. In which of the following, a separate schema is created consisting of that attribute and the primary key of the entity set.

a. A many-to-many relationship set

b. A multivalued attribute of an entity set

c. A one-to-many relationship set

d. All of the mentioned

Answer» B. A multivalued attribute of an entity set.

Ques 37. Relation dept year(dept name, total inst 2007, total inst 2008, total inst 2009). Here the only functional dependencies are from dept name to the other attributes. This relation is in

a. Fourth NF

b. BCNF

c. Third NF

d. Second NF

Answer» B. BCNF

Ques 38. Representations such as the in the dept year relation, with one column for each value of an attribute, are called _______ they are widely used in spreadsheets and reports and in data analysis tools.

a. Cross-tabs

b. Snapshot

c. Both Cross-tabs and Snapshot

d. All of the mentioned

Ques 39. Data Models in DBMS are classified into ______ categories.

a. 3

b. 2

c. 5

d. 4

Answer» C. 5

Ques 40. We indicate roles in E-R diagrams by labeling the lines that connect ___________ to __________

a. Diamond , diamond

b. Rectangle, diamond

c. Rectangle, rectangle

d. Diamond, rectangle

Answer» D. Diamond, rectangle

Ques 41. For a weak entity set to be meaningful, it must be associated with another entity set, called the

a. Identifying set

b. Owner set

c. Neighbour set

d. Strong entity set

Answer: a. Identifying set

Ques 42. An audit trail ___________

a. Is used to make backup copies

b. Is the recorded history of operations performed on a file

c. Can be used to restore lost information

d. None of the mentioned

Answer: B. Is the recorded history of operations performed on a file

Ques 43. A relational database system needs to maintain data about the relations, such as the schema of the relations. This is called

a. Metadata

b. Catalog

c. Log

d. Dictionary

Answer a. Metadata

Ques 44. A tablespace is further broken down into ________

a. Tablespace

b. Segments

c. Extents

d. Blocks

Answer: b. Segments

 Ques 45 Which of the following is a fundamental operation in relational algebra?
a) Set intersection
b) Natural join
c) Assignment
d) None of the mentioned

Answer: d
Explanation: The fundamental operations are select, project, union, set difference, Cartesian product, and rename.

Ques 46 The ___________ operation, denoted by −, allows us to find tuples that are in one relation but are not in another.
a) Union
b) Set-difference
c) Difference
d) Intersection

Answer: b
Explanation: The expression r − s produces a relation containing those tuples in r but not in s.

 Ques 47. Which is a unary operation:
a) Selection operation
b) Primitive operation
c) Projection operation
d) Generalized selection

Answer: d
Explanation: Generalization Selection takes only one argument for operation.

Ques 48 How many types of relational operations are there?

1. 6
2. 7
3. 8
4. 9

Answer: B) 7

Explanation:

There are 7 relational operations.

1. Select Operation
2. Project Operation
3. Union Operation
4. Set Intersection
5. Set Difference
6. Cartesian Product
7. Rename Operation

Ques 49. Which of the following is NOT a type of relational operation?

1. Select Operation
2. Set Difference
3. Set Update
4. Cartesian Product

Answer: C) Set Update

Explanation:

Set Update is NOT a type of relational operation.

Ques 50 Select operation is denoted by –

1. σ
2. R
3. P
4. S

Answer: A) σ

Explanation:

Select operation is denoted by σ.

Ques 51. A list of the attributes we wish to appear in the result is displayed in ___ operation.

1. Select
2. Project
3. Union
4. Rename

Answer: B) Project

Explanation:

A list of the attributes we wish to appear in the result is displayed in Project operation.

Ques 52. What is Project Operation denoted by –

1. P
2. R
3. O
4. ∏

Answer: D) ∏

Explanation:

Project Operation is denoted by ∏.