Samacheer Kalvi 12th Computer Science Guide Chapter 11 Database Concepts

Tamilnadu State Board New Syllabus Samacheer Kalvi 12th Computer Science Guide Pdf Chapter 11 Database Concepts Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 12th Computer Science Solutions Chapter 11 Database Concepts

12th Computer Science Guide Database Concepts Text Book Questions and Answers

I. Choose the best answer (1 Marks)

Question 1.
What is the acronym of DBMS?
a) Data Base Management Symbol
b) Database Managing System
c) Data Base Management System
d) DataBasic Management System
Answer:
c) Data Base Management System

Question 2.
A table is known as
a) tuple
b) attribute
c) relation
d) entity
Answer:
c) relation

Question 3.
Which database model represents parent-child relationship?
a) Relational
b) Network
c) Hierarchical
d) Object
Answer:
c) Hierarchical

Question 4.
Relational database model was first proposed by
a) E F Codd
b) E E Codd
c) E F Cadd
d) E F Codder
Answer:
a) E F Codd

Question 5.
What type of relationship does hierarchical model represents?
a) one-to-one
b) one-to-many
c) many-to-one
d) many-to-many
Answer:
b) one-to-many

Question 6.
Who is called Father of Relational Database from the following?
a) Chris Date
b) Hugh Darween
c) Edgar Frank Codd
d) Edgar Frank Cadd
Answer:
c) Edgar Frank Codd

Question 7.
Which of the following is an RDBMS?
a) Dbase
b) Foxpro
c) Microsoft Access
d) SQLite
Answer:
d) SQLite

Question 8.
What symbol is used for SELECT statement?
a) o
b) n
c) X
d) Q
Answer:
a) o

Question 9.
A tuple is also known as
a) table
b) row
c) attribute
d) field
Answer:
b) row

Question 10.
Who developed ER model?
a) Chen
b) EF Codd
c) Chend
d) Chand
Answer:
a) Chen

II. Answer the following questions (2 Marks)

Question 1.
Mention few examples of a database.
Answer:
dbase-III , dbase-III Plus, Foxbase , Foxpro ,SQL Server, Oracle Database, Sybase, Informix, MySQL are some examples of Database languages which are used to design ERP applications like Payroll, Railway Reservation System, Inventory Systems.

Question 2.
List some examples of RDBMS.
Answer:
SQL Server, Oracle Database, Sybase, Informix, MySQL.

Question 3.
What is data consistency?
Answer:
Data Consistency
On live data, it is being continuously updated and added, maintaining the consistency of data can become a challenge. But DBMS handles it by itself. Data Consistency means that data values are the same at all instances of a database.

Question 4.
What is the difference between the Hierarchical and Network data model?
Answer:

Hierarchical Data Model		Network Data Model
1	A child record has only one parent node	A child may have many parent nodes
2	It represents the data in one-to-many relationships	It represents the data in many-to-many relationships
3	This model is not easier and faster to access the data than the Network data model.	This model is easier and faster to access the data.

Question 5.
What is normalization?
Answer:

• Normalization is a process of organizing the data in the database to avoid data redundancy and to improve data integrity.
• Database normalization was first proposed by Dr. Edgar F Codd as an integral part of RDBMS. These rules are known as the E F Codd Rules.

III. Answer the following questions (3 Marks)

Question 1.
What is the difference between Select and Project
Answer:

Select	Project
The SELECT operation(o) is used for selecting a subset with tuples according to a given selection condition.	The projection method(n) eliminates all attributes of the input relation but those mentioned in the projection list.
The SELECT operation (o) selects filters out all tuples that do not satisfy the condition.	The projection method defines a relation that contains a vertical subset of Relation.
Symbol: σ	Symbol: π
General Form: σ (R) c Example: σ = “Big Data” (STUDENT) course	Example: π  (STUDENT) course

Question 2.
What is the role of DBA?
Answer:

1. Database Administrator or DBA is the one who manages the complete database management system.
2. DBA takes care of the security of the DBMS, managing the license keys, managing user accounts and access etc.

Question 3.
Explain Cartesian Product with a suitable example.
Answer:

• Cross product is a way of combining two relations.
• The resulting relation contains, both relations being combined.
• A x B means A times B, where the relation A and B have different attributes.
• This type of operation is helpful to merge columns from two relations

studno	name	studno	subject
cs1	Kannan	cs28	Big Data
cs2	Gowri Shankar	cs62	R language
cs4	Padmaja	cs25	Python Programming

Cartesian product; Table A x Table B

studno	name	course	subject
cs1	Kannan	cs28	Big Data
cs1	Kannan	cs62	. R language
cs1	Kannan	cs25	Python Programming
cs2	Gowri Shankar	cs28	Big Data
cs2	Gowri Shankar	cs’62	R language
cs2	Gowri Shankar	cs25	Python Programming
cs4	Padmaja	cs28	Big Data
cs4	Padmaja	cs62	R language
cs4	Padmaja	cs25	Python Programming

Question 4.
Explain the Object Model with an example.
Answer:
Object Model:

• Object model stores the data in the form of objects, attributes and methods, classes and inheritance.
• This model handles more complex applications, such as Geographic Information System (GIS), scientific experiments, engineering design and manufacturing.
• It is used in file Management System.
• It represents real-world objects, attributes and behaviours.
• It provides a clear modular structure.
• It is easy to maintain and modify the existing code.

An example of the Object model is : Shape

Circle, Rectangle, and Triangle are all objects in this model

• The circle has the attribute radius.
• Rectangle has the length and breadth of the attribute.
• Triangle has the attributes base and height.
• The objects Circle, Rectangle, and Triangle inherit from the object Shape.

Question 5.
Write a note on different types of DBMS users.
Answer:
Types of DBMS Users
(i) Database Administrator:
Database Administrator or DBA is the one who manages the complete database management system. DBA takes care of the security of the DBMS, managing the license keys, managing user accounts and access etc.

(ii) Application Programmers or Software Developers:
This user group is involved in developing and designing the parts of DBMS.

(iii) End User:
End users are the ones who stores, retrieve, update and delete data.

(iv) Database designers: are responsible for identifying the data to be stored in the database for choosing appropriate structures to represent and store the data.

IV. Answer the following questions (5 Marks)

Question 1.
Explain the different types of data models.
Answer:
The different types of a Data Model are:

1. Hierarchical Model,
2. Relational Model,
3. Network Database Model,
4. Entity-Relationship Model,
5. Object Model.

Hierarchical Model:

• The hierarchical model was developed by IBM as Information Management System.
• In the Hierarchical model, data is represented as a simple tree-like structure form.
• This model represents a one-to-many relationship i.e., parent-child relationship.
• One child can have only one parent but one parent can have many children.
• This model is mainly used in IBM Main Frame computers.

Relational Model:

• The Relational Database model was first proposed by E.F. Codd in 1970.
• Nowadays, it is the most widespread data model used for database applications around the world.
• The basic structure of data in the relational model is tabling (relations).
• All the information related to a particular type is stored in rows of that table.
• Hence tables are also known as relations in a relational model.
• A relation key is an attribute that uniquely identifies a particular tuple (row in a relation (table)).

Network Model:
A network database model is an extended form of the hierarchical data model.
The difference between hierarchical and Network data model is:

• In a hierarchical model, a child record has only one parent node,
• In a Network model, a child may have many parent nodes.
• It represents the data in many-to-many relationships.
• This model is easier and faster to access the data.

Example:

• School represents the parent node
• Library, Office, and Staffroom is a child to school (parent node)
• Student is a child in the library, office and staff room (one to many relationships)

Entity-Relationship Model. (ER model):

• In this database model, relationships are created by dividing the object into the entity and its characteristics into attributes.
• It was developed by Chen in 1976.
• This model is useful in developing a conceptual design for the database.
• It is very simple and easy to design a logical view of data.
• The developer can easily understand the system by looking at ER model constructed.
• The rectangle represents the entities.

Example. Doctor and Patient.

• Ellipse represents the attributes
  E.g. D-id, D-name, P-id, P-name.
• Attributes describe the characteristics and each entity becomes a major part of the data stored in the database.
• The diamond represents the relationship in ER diagrams e.g; Doctor diagnosis the Patient

Object Model:

• Object model stores the data in the form of objects, attributes, and methods, classes, and Inheritance.
• This model handles more complex applications, such as Geographic Information System (GIS), scientific experiments, engineering design, and manufacturing.
• It is used in the file Management System.
• It represents real-world objects, attributes, and behaviours.
• It provides a clear modular structure. It is easy to maintain and modify the existing code.

Example of the Object model is Shape,
Circle, Rectangle and Triangle are all objects in this model

• The circle has the attribute radius.
• Rectangle has the length and breadth of the attribute.
• Triangle has the attributes base and height.
• The objects Circle, Rectangle, and Triangle inherit from the object Shape.

Question 2.
Explain the different types of relationship mapping.
Answer:
The types of relationships used in a database are

• One-to-One Relationship
• One-to-Many Relationship
• Many-to-One Relationship
• Many-to-Many Relationship

One-to-One Relationship:

• In One-to-One Relationship, one entity is related with only one other entity.
• One row in a table is linked with only one row in another table and vice versa. Example: A student can have only one exam number.

One-to-Many Relationship:

• In a One-to-Many relationship, one entity is related to many other entities.
• One row in table A is linked to many rows in table B, but one row in table B is linked to only one row in table A. Example: One Department has many staff members.

Many to-one Relationship

• In Many-to-One Relationship, many entities can be related with only one in the other entity.
• Example: A number of staff members working in one Department. Multiple rows in staff members table is related with only one row in Department table.

Many-to-Many Relationship:

• A many-to-many relationships occurs when multiple records in a table are associated with multiple records in another table.
• Example 1: Customers and Product

Customers can purchase various products and Products can be purchased by many customers.

Example 2: Students and Courses
A student can register for many Courses and a Course may include many students

Example 3: Books and Student.
Many Books in a Library are issued to many students.

Question 3.
Differentiate DBMS and RDBMS.
Answer:

Basis of Comparison	DBMS	RDBMS
Expansion	Database Management System	Relational Database Management System
Data storage	Navigational model ie data by linked records	Relational model (in tables), ie data in tables as row and column
Data redundancy	Exhibit	Not Present
Normalization	Not performed	RDBMS uses normalization to reduce redundancy
Data access	Consumes more time	Faster, compared to DBMS.
Keys and indexes	Does not use.	used to establish a relationship. Keys are used in RDBMS.
Transaction management	Inefficient, Error-prone, and insecure	Efficient and secure.
Distributed Databases	Not supported	Supported by RDBMS.
Example	Dbase, FoxPro.	SQL Server, Oracle, MySQL, MariaDB, SQLite.

Question 4.
Explain the different operators in Relational algebra with suitable examples.
Answer:
Relational Algebra is divided into various groups:
Unary Relational Operations:

1. SELECT (symbol: σ)
2. PROJECT (symbol: π)

Relational Algebra Operations from Set Theory:

1. UNION (U)
2. INTERSECTION (∩)
3. DIFFERENCE (-)
4. CARTESIAN PRODUCT (X)

SELECT symbol: σ_c (R) with a relation R and a condition C on the attributes of R

• The SELECT operation is used for selecting a subset with tuples according to a given condition.
• Select filters out all tuples that do not satisfy C

Table A : STUDENT :

Studno	Name	Course	Year
cs1	Kannan	Big Data	II
cs2	Gowri Shankar	R Language	I
cs3	Lenin	Big Data	I
cs4	Padmaja	Python Programming	I

σ_course = <Big Data> (Student)

Studno	Name	Course	Year
csl	Kannan	Big Data	II
cs2	Lenin	Big Data	I

PROJECT (symbol: n):

• The projection eliminates all attributes of the input relation but those mentioned in the projection list.
• The projection method defines a relation that contains a vertical subset of Relation.
• Example 1 using Table A
  π_course (STUDENT)

Result:

Course :

Big Data

R language

Python Programming

Example 2 (using Table A)
π_{student, course} (STUDENT)

Studno	Course
cs1	Big Data
cs2	R language
cs3	Big Data
cs4	Python Programming

UNION (Symbol: U):

• It includes all tuples that are in tables A or in B.
• It also eliminates duplicates.
• Set A Union Set B would be expressed as A U B

Example 3
Consider the following tables

Table A
Studno	Name
cs1	Kannan
cs2	Lenin
cs3	Padmaja

Table B
Studno	Name
cs1	Kannan
cs2	Lenin
cs3	Padmaja

Result (A U B)

Table A
Studno	Name
cs1	Kannan
cs2	Gowrishankaran
cs3	Lenin
cs4	Padmaja

SET DIFFERENCE ( Symbol: -):

• The result of A – B, is a relation which includes all tuples that are in A but not in B.
• The attribute name of A has to match with the attribute name in B.
• Example 4 (using Table B):

Result:

Table
Cs4	Padmaja

INTERSECTION (symbol: ∩) A ∩ B:

• INTERSECTION Defines a relation consisting of a set of all tuple that are in both in A and B.
• However, A and B must be union-compatible.

Example 5 (using Table B)

Table A – B
cs1	Kannan
cs3	Lenin

PRODUCT OR CARTESIAN PRODUCT (Symbol: X)

• Cross product is a way of combining two relations. The resulting relation contains, both relations being combined.
• A x B means A times B, where the relation A and B have different attributes.
• This type of operation is helpful to merge columns from two relations.

Table A		‘                   Table B
studno	name	studno	subject
cs1	Kannan	cs28	Big Data
cs2	Gowri Shankar	cs62	R language
cs4	Padmaja	cs25	Python Programming

studno	name	course	subject
csl	Kannan	cs28	Big Data
csl	Kannan	cs62	R language
csl	Kannan	cs25	Python Programming
cs2	Gowri Shankar	cs28	Big Data
cs2	Gowri Shankar	cs62	R language
cs2	Gowri Shankar	cs25	Python Programming
cs4	Padmaja	cs28	Big Data
cs4	Padmaja	cs62	R language
cs4	Padmaja	cs25	Python Programming

Question 5.
Explain the characteristics of DBMS.
Answer:
Characteristics of Database Management system:

Data stored in Table	Data is never directly stored in the database. Data is stored in tables, created inside the database. DBMS also allows having relationships between tables which makes the data more meaningful and connected.
Reduced Redundancy	In the modern world, hard drives are very cheap, but earlier when hard drives were too expensive, unnecessary repetition of data in databases was a big problem But DBMS follows Normalization which divides the data in such a way that repetition is minimum.
Data Consistency	On live data, it is being continuously updated and added, maintaining the consistency of data can become a challenge. But DBMS handles it by itself.
Support Multiple user and Concurrent Access	DBMS allows multiple users to work on it( update, insert, delete data) at the same time and still manages to maintain data consistency.
Query Language	DBMS provides users with a simple query language, using which data can be easily fetched, inserted, deleted, and updated in a database.
Security	The DBMS also takes care of the security of data, protecting the data from unauthorized access. In a typical DBMS, we can create user accounts with different access permissions, using which we can easily secure our data by restricting user access.
DBMS Supports Transac­tions	It allows us to better handle and manage data integrity in real-world applications where multi-threading is extensively used.

12th Computer Science Guide Database Concepts Additional Important Questions and Answers

I. Choose the best answer (1 Mark)

Question 1.
…………………… are raw facts stored in a computer
(a) data
(b) Information
(c) row
(d) tuple
Answer:
(a) data

Question 2.
………………….is an organized collection of data, which can be stored and accessed electronically from a computer system
a) Worksheet
b) Database
c) DBMS
d) Information
Answer:
b) Database

Question 3.
……………………. is a repository collection of related data
(a) data
(b) Information
(c) database
(d) tuple
Answer:
(c) database

Question 4.
In………………….data are organized in a way that, they can be easily accessed, managed, and updated.
a) Database
b) Pointer
c) Structure
d) Object
Answer:
a) Database

Question 5.
………………….allows users to store, process, and analyze data easily.
a) My SQL
c) My SQL SQLite
b) Relational Algebra
d) DBMS
Answer:
d) DBMS

Question 6.
Find the wrong statement about DBMS?
(a) segregation of application program
(b) Maximum data Redundancy
(c) Easy retrieval of data
(d) Reduced development time
Answer:
(b) Maximum data Redundancy

Question 7.
…………………. provides protection and security to the databases
a) MySQL
b) DBMS
c) Oracle
d) Ingress
Answer:
b) DBMS

Question 8.
…………………. can be software or hardware-based, with one sole purpose of storing data.
a) MySQL
b) DBMS
c) Database
d) Ingress
Answer:
c) Database

Question 9.
Which is the language used to write commands to access, insert, update data stored in the database?
(a) DataBase Access Languages
(b) Javascript
(c) Basic
(d) Foxpro
Answer:
(a) DataBase Access Languages

Question 10.
…………………. major components are there in DBMS?
a) Four
b) Three
c) Five
d) Two
Answer:
c) Five

Question 11.
…………………. characteristics of DBMS allows to better handle and manage data integrity
a) Data redundancy
b) Data security
c) DBMS Supports Transactions
d) Data integrity
Answer:
c) DBMS Supports Transactions

Question 12.
…………………. DBMS components that manage databases to take backups, report generation.
a) Software
b) Hardware
c) Data
d) Procedures/Methods
Answer:
d) Procedures/Methods

Question 13.
…………………. in a table represents a record.
a) Row
b) Column
c) File
d) Data
Answer:
a) Row

Question 14.
Which of the following is not a DBMS component?
a) Hardware/ Software
b) Data
c) Procedures
d) Data model
Answer:
d) Data model

Question 15.
Hierarchical Model was developed by ……………………….
(a) Apple
(b) IBM
(c) Microsoft
(d) Macromedia
Answer:
(b) IBM

Question 16.
…………………. is not a type of data model?
a) Hierarchical model
b) Entity-Relationship model
c) Object model
d) Redundancy model
Answer:
d) Redundancy model

Question 17.
…………………. is an extended form of hierarchical data model.
a) ER model
b) Hierarchical mode
c) Network database model
d) Object model
Answer:
c) Network database model

Question 18.
The relational model was developed in the year ……………………..
(a) 1980
(b) 1970
(c) 1965
(d) 1985
Answer:
(b) 1970

Question 19.
The abbreviation of GIS is
a) Global Information System
b) Geographic Information System
c) Global Information Source
d) Geographic Intelligent System
Answer:
b) Geographic Information System

Question 20.
Data is represented as a simple tree-like structure form in the data model
a) Network database
b) Hierarchical model
c) ER model
d) Relational model
Answer:
b) Hierarchical model

Question 21.
ER Model Expand ………………………..
(a) Entry Relation
(b) Entity Relationship
(c) Entire Row
(d) Entity Row
Answer:
(b) Entity Relationship

Question 22.
…………………. takes care of the security of the DBMS, managing the license keys, managing user accounts and access.
a) Database Designer
b) Database Administrator
c) Database Architect
d) Data Analyst
Answer:
b) Database Administrator

Question 23.
The …………………. operation is used for selecting a subset with tuples according
to a given condition.
a) CARTESIAN PRODUCT
b) SELECT
c) Union
d) Intersection
Answer:
b) SELECT

Question 24.
Find the wrongly matched pair.
(a) Entities – Rectangle
(b) Ellipse – attributes
(c) Diamond – relationship
(d) row – square
Answer:
(d) row – square

II. Answer the following questions (2 and 3 Marks)

Question 1.
What is a database?
Answer:

• The database is a repository collection of related data organized in a way that data can be easily accessed, managed, and updated.
• The database can be software or hardware-based, with one sole purpose of storing data.

Question 2.
Write the advantages of DBMS.
Answer:

• Segrega n f application program
• Minimal date duplication or Data Redundancy
• Easy retrieval of data using the Query Language
• Reduced development time and maintenance

Question 3.
Define Data and Information.
Answer:

Data	Information
Data are raw facts stored in a computer	Information is formatted data
Data may contain any character, text, word, or number.	The information allows being utilized in a significant way

Question 4.
Define Table?
Answer:
Table is the entire collection of related data in one table, referred to as a File or Table where the data is organized as row and column.

Question 5.
Define: Database structure
Answer:

• Table is the entire collection of related data in one table, referred to as a File or Table where the data is organized as row and column.
• Each row in a table represents a record, which is a set of data for each database entry.
• Each table column represents a Field, which groups each piece or item of data among the records into specific categories or types of data.

Example: StuNo., StuName, StuAge, StuClass, StuSec.,

• A Table is known as a RELATION S
• A Row is known as a TUPLE S
• A column is known as an ATTRIBUTE

Question 6.
Write a note on relational Algebra?
Answer:
Relational Algebra is a procedural query language used to query the database tables using SQL. Relational algebra operations are performed recursively on a relation (table) to yield output.

Question 7.
What is Data model?
Answer:

• A data model describes how the data can be represented and accessed from the software after complete implementation.
• It is a simple abstraction of a complex real-world data gathering environment.
• The main purpose of the data model is to give an idea of how the final system or software will look after development is completed.

Question 8.
What is Relational Algebra?
Answer:

• Relational Algebra, was first created by Edgar F Codd while at IBM.
• It was used for modeling the data stored in relational databases and defining queries on it.
• Relational Algebra is a procedural query language used to query the database tables using SQL.
• Relational algebra operations are performed recursively on a relation (table) to yield an output.
• The output of these operations is a new relation, which might be formed by one or more input relations.

Question 9.
List the types of data model.
Answer:

• Hierarchical Model
• Relational Model
• Network Database Model
• Entity-Relationship Model
• Object Model

Question 10.
List the types of DBMS users.
Answer:

• Database Administrators (DBA)
• Application or software developers
• End-User
• Database designers

Question 11.
Write short notes on Relational Data Model.
Answer:

• The Relational Database model was first proposed by E.F. Codd in 1970 . Nowadays, it is the most widespread data model used for database applications around the world.
• The basic structure of data in the relational model is tables (relations). All the information related to a particular type is stored in rows of that table. Hence tables are also known as relations in a relational model. A relation key is an attribute which uniquely identifies a particular tuple.

III. Answer the following questions (5 Marks)

Question 1.
Explain the components of DBMS
Answer:
The Database Management System can be divided into five major components namely 1. Hardware, 2. Software, 3. Data, 4. Procedures/Methods
5. Database Access Languages

1. Hardware:
The computer, hard disk, I/O channels for data, and any other physical component involved in the storage of data

2. Software:
This main component is a program that controls everything.
The DBMS software is capable of understanding the Database Access Languages and interprets them into database commands for execution.

3. Data:
It is that resource for which DBMS is designed. DBMS creation is to store and utilize data.

4. Procedures/ Methods:
They are general instructions to use a database management system such as the installation of DBMS, manage databases to take backups, report generation, etc

5. DataBase Access Languages :

• They are the languages used to write commands to access, insert, update and delete data stored in any database.
• Examples of popular DBMS: Dbase, FoxPro