Computer Science · Chapter 02

72 solved questions

Database Management System

Every question in this chapter, answered and explained — step-by-step solutions drawn live from the chapter library across 8 question sections.

Textbook-Based Content: Multiple Choice Questions15 Textbook-Based Content: Write the Tech Terms15 Textbook-Based Content: Descriptive Questions (Brief)16 Textbook-Based Content: Descriptive Questions (Comprehensive)14 Level 1 — Basic4 Level 2 — Standard3 Level 3 — SEE Style3 Level 4 — Application2

Textbook-Based Content: Multiple Choice Questions

1Textbookcs1-q1

Which of the following is used to uniquely identify each row in a table? a) Foreign Key b) Primary Key c) Attribute d) Column

Ans.b) Primary Key

2Textbookcs1-q2

In a table, the vertical arrangement of data is called a: a) Field Name b) Row c) Column d) Record

Ans.c) Column

3Textbookcs1-q3

Which one is an example of open-source database software? a) Oracle b) MySQL c) MS Access d) MS Excel

Ans.b) MySQL

4Textbookcs1-q4

What type of SQL command is used to insert new records into a table? a) CREATE b) INSERT c) UPDATE d) SELECT

Ans.b) INSERT

5Textbookcs1-q5

Which clause is used in SQL to filter records based on a specific condition? a) ORDER BY b) WHERE c) SET d) VALUES

Ans.b) WHERE

6Textbookcs1-q6

Which command is used to permanently delete a table from a database? a) DELETE b) DROP c) REMOVE d) ERASE

Ans.b) DROP

7Textbookcs1-q7

Which command is used to retrieve data from a table in MySQL? a) SELECT b) INSERT c) DELETE d) UPDATE

Ans.a) SELECT

8Textbookcs1-q8

Which of the following is a DML command? a) CREATE b) SELECT c) DROP d) ALTER

Ans.b) SELECT

9Textbookcs1-q9

The command that changes the structure of an existing table is: a) CREATE b) ALTER c) INSERT d) SELECT

Ans.b) ALTER

10Textbookcs1-q10

Which of these data types is suitable to store textual information of variable length? a) INT b) FLOAT c) VARCHAR d) DATE

Ans.c) VARCHAR

11Textbookcs1-q11

Which of these is a correct relational operator in SQL? a) ADD b) > c) PUT d) LINK

Ans.b) >

12Textbookcs1-q12

Which clause is used to sort the result in ascending or descending order? a) ORDER BY b) SORT c) GROUP d) WHERE

Ans.a) ORDER BY

13Textbookcs1-q13

Which operator is used to select values between two ranges in SQL? a) LIKE b) IN c) BETWEEN d) IS

Ans.c) BETWEEN

14Textbookcs1-q14

A command to modify existing data within a table is: a) INSERT b) UPDATE c) DELETE d) CREATE

Ans.b) UPDATE

15Textbookcs1-q15

Which type of key is used to link one table with another table's primary key? a) Candidate Key b) Foreign Key c) Primary Key d) Composite Key

Ans.b) Foreign Key

Textbook-Based Content: Write the Tech Terms

1Textbookcs2-q1

A software used to create, manage, and use databases.

Ans.DBMS (Database Management System)

2Textbookcs2-q2

An organized collection of related data stored in a computer system.

Ans.Database

3Textbookcs2-q3

Raw facts or figures that have no clear meaning until arranged.

Ans.Data

4Textbookcs2-q4

Organized and meaningful data obtained after processing.

Ans.Information

5Textbookcs2-q5

A column in a table that uniquely identifies each row.

Ans.Primary Key

6Textbookcs2-q6

A column in one table that connects to the primary key of another table.

Ans.Foreign Key

7Textbookcs2-q7

A command in MySQL used to add new data into a table.

Ans.INSERT

8Textbookcs2-q8

A DDL command used to make a new table.

Ans.CREATE

9Textbookcs2-q9

A DML command used to modify existing records in a table.

Ans.UPDATE

10Textbookcs2-q10

A clause used to filter records based on a given condition.

Ans.WHERE

11Textbookcs2-q11

A clause used to sort records in ascending or descending order.

Ans.ORDER BY

12Textbookcs2-q12

A set of symbols or keywords used to perform operations in SQL.

Ans.Operator

13Textbookcs2-q13

A command used to retrieve and display data from one or more tables.

Ans.SELECT

14Textbookcs2-q14

A DDL command used to permanently delete a table or database.

Ans.DROP

15Textbookcs2-q15

A command given to a database to perform a task like add, search, or delete.

Ans.Command

Textbook-Based Content: Descriptive Questions (Brief)

1Textbookcs3-q1

What is the main difference between data and information?

Ans.Data is raw, unprocessed facts or figures with no clear meaning on their own (e.g., 80, Nepal), while information is meaningful and organized data that has been processed to make sense (e.g., 'Rina scored 80 marks in Math').

2Textbookcs3-q2

Define DBMS with one clear example.

Ans.A DBMS (Database Management System) is software that helps to create, manage, and use databases, allowing users to store, add, delete, update, and search data safely. Example: MySQL.

3Textbookcs3-q3

What is RDBMS?

Ans.RDBMS (Relational Database Management System) is a DBMS technology that stores data in tables of rows and columns, where relationships between tables are established using keys, and it supports SQL commands.

4Textbookcs3-q4

Why is a primary key important in a database table?

Ans.A primary key is important because it uniquely identifies each row in a table, ensures no duplicate or empty values exist, and helps to quickly find and manage data.

5Textbookcs3-q5

Write the use of the FOREIGN KEY in relational databases.

Ans.A Foreign Key is used to create a relationship between two tables by linking a column in one table to the primary key of another table, ensuring data consistency across tables.

6Textbookcs3-q6

What is the purpose of the CREATE command in MySQL?

Ans.The CREATE command is used to make a new database or a new table, defining its structure such as columns and data types.

7Textbookcs3-q7

Name any two DDL commands.

Ans.CREATE and ALTER are two DDL commands. (DROP, TRUNCATE, and RENAME are also valid.)

8Textbookcs3-q8

Why do we use the SELECT command in MySQL?

Ans.The SELECT command is used to retrieve and display data from one or more tables in a database, allowing users to view specific or all columns, with optional filtering and sorting.

9Textbookcs3-q9

List any two examples of clauses used with SQL statements.

Ans.WHERE (to filter records) and ORDER BY (to sort results) are two examples of clauses used with SQL statements.

10Textbookcs3-q10

What is the function of the ORDER BY clause in MySQL?

Ans.The ORDER BY clause is used to sort the result of a query in ascending (ASC) or descending (DESC) order based on one or more columns.

11Textbookcs3-q11

Which command is used to remove specific records from a table? Write its syntax.

Ans.The DELETE command is used to remove specific records from a table. Syntax: DELETE FROM table_name WHERE condition;

12Textbookcs3-q12

Write any two differences between DDL and DML commands.

Ans.DDL commands (like CREATE, ALTER, DROP) define and manage the database structure, while DML commands (like INSERT, UPDATE, DELETE) manage the data inside the tables. DDL changes affect the table's design; DML changes affect the table's records.

13Textbookcs3-q13

Write any two reasons why we use a database management system (DBMS) in computing.

Ans.A DBMS is used because it allows organized storage of large amounts of data and provides quick, easy access to that data, along with security and multi-user support.

14Textbookcs3-q14

What do you mean by redundancy in a database system?

Ans.Redundancy means the same data is stored more than once in different places in a database, which wastes storage and can cause inconsistency when the data is updated in only one location.

15Textbookcs3-q15

Why should the WHERE clause be used carefully with UPDATE and DELETE commands?

Ans.The WHERE clause must be used carefully with UPDATE and DELETE because if it is omitted, the command will affect all records in the table, which could unintentionally change or delete the entire dataset.

16Textbookcs3-q16

What is a relationship in MySQL?

Ans.A relationship in MySQL defines how data in one table is connected to data in another table, usually established using primary keys and foreign keys. Common types are One-to-One, One-to-Many, and Many-to-Many.

Textbook-Based Content: Descriptive Questions (Comprehensive)

1Textbookcs4-q1

Explain the differences between a database and a DBMS with examples.

Ans.A database is an organized collection of related data, such as a Student table containing names, ages, and addresses. A DBMS is the software used to create, manage, and interact with that database, such as MySQL. In short, the database is the actual data storage, while the DBMS is the tool used to manage that storage — for example, MySQL (DBMS) is used to create and manage the SchoolDB database (database) containing student records.

2Textbookcs4-q2

What is a primary key? List any four features or functions of a primary key in a table.

Ans.A Primary Key is a column or set of columns in a table that uniquely identifies each row. Features: (i) It uniquely identifies each row in a table. (ii) No two rows can have the same primary key value. (iii) It cannot have a null (empty) value. (iv) It helps to quickly find and manage data in the table.

3Textbookcs4-q3

What is the purpose of the FOREIGN KEY in MySQL? Explain with a suitable example.

Ans.The FOREIGN KEY is used to create a relationship between two tables by linking a column in one table to the primary key of another table, ensuring only valid, matching values are stored. Example: In a Marks table, Student_ID is a Foreign Key that connects to the ID column in the Student table, ensuring that marks can only be entered for students that already exist in the Student table.

4Textbookcs4-q4

Write the differences between DDL and DML commands with any two examples each.

Ans.DDL (Data Definition Language) commands define and manage the structure of the database, such as tables and columns, without affecting the actual data. Examples: CREATE TABLE Student (...); and ALTER TABLE Student ADD Grade VARCHAR(10); DML (Data Manipulation Language) commands manage the data inside the tables, such as adding, updating, or deleting records, without changing the table structure. Examples: INSERT INTO Student VALUES (1,'Ram',18,'Kathmandu'); and UPDATE Student SET Age=19 WHERE ID=1;

5Textbookcs4-q5

Describe the function of the following SQL commands: CREATE, DROP, INSERT, and SELECT.

Ans.CREATE is used to make a new database or table, defining its structure. DROP is used to permanently delete an entire table or database along with its structure and data. INSERT is used to add new records (rows) into a table. SELECT is used to retrieve and display data from one or more tables, optionally filtered or sorted using clauses like WHERE and ORDER BY.

6Textbookcs4-q6

What are clauses in SQL? Explain the uses of WHERE, ORDER BY, and GROUP BY clauses.

Ans.A clause is a part of an SQL statement that adds extra conditions, rules, or arrangements to control how data is retrieved, updated, or deleted. WHERE filters records based on a condition, for example SELECT * FROM Student WHERE Age > 15; ORDER BY sorts the result in ascending or descending order, for example SELECT * FROM Student ORDER BY Age DESC; GROUP BY groups records that have the same values in specified columns, which is useful for producing summarized results such as counting the number of students per class.

7Textbookcs4-q7

Define operators in SQL. List any four relational operators with examples.

Ans.Operators in SQL are special symbols or keywords used to perform operations on values or expressions, mostly used in WHERE clauses and conditions. Four relational operators: (i) = — checks equality, e.g., WHERE City = 'Pokhara'; (ii) != — checks not equal, e.g., WHERE City != 'Pokhara'; (iii) > — greater than, e.g., WHERE Age > 15; (iv) BETWEEN — checks a range, e.g., WHERE Age BETWEEN 14 AND 16.

8Textbookcs4-q8

What is a query in MySQL? Explain how queries help in managing database records.

Ans.A query is a command given to a MySQL database to work with data — to add, search, update, or delete information — written using SQL statements. Queries help manage database records by allowing users to retrieve exactly the information they need (using SELECT with WHERE), modify existing records (using UPDATE), remove unwanted records (using DELETE), and add new ones (using INSERT), all without manually searching through the entire table.

9Textbookcs4-q9

Explain with examples how the UPDATE and DELETE commands work with the WHERE clause.

Ans.The UPDATE command modifies existing records, and the WHERE clause decides which record(s) are changed. Example: UPDATE Student SET City='Bhaktapur' WHERE Name='Sita'; — this changes only Sita's city, leaving other records unchanged. The DELETE command removes records, and WHERE decides which ones are removed. Example: DELETE FROM Employee WHERE Name='Hari'; — this removes only Hari's record. In both cases, omitting the WHERE clause would affect all records in the table.

10Textbookcs4-q10

Write the importance of using a DBMS in computing. Mention any four advantages of a DBMS.

Ans.A DBMS is important because it allows large amounts of data to be stored, accessed, and managed efficiently and securely, replacing slow and error-prone manual record-keeping. Four advantages: (i) Reduces data redundancy. (ii) Ensures data consistency and integrity. (iii) Improves data security by restricting unauthorized access. (iv) Supports multi-user access and provides backup and recovery.

11Textbookcs4-q11

What are SQL constraints? State their importance.

Ans.SQL constraints are rules applied to table columns to maintain the accuracy and reliability of data, such as PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL, CHECK, and DEFAULT. Their importance includes maintaining data accuracy by restricting invalid values, ensuring data consistency across related tables, preventing duplicate entries, enforcing relationships between tables, and helping in error-free data entry.

12Textbookcs4-q12

What do you mean by a report in MySQL? How does it help users?

Ans.A report in MySQL is a final, organized output of data collected from one or more tables, typically produced using a SELECT query, such as SELECT * FROM Student WHERE Age > 14; It helps users by presenting selected information like lists, summaries, or analysis in a clear, arranged way rather than showing the raw, unfiltered table.

13Textbookcs4-q13

Define a composite key. Explain when it is used in a database.

Ans.A composite key is a combination of two or more columns used together to uniquely identify a record in a table. It is used when no single column is unique enough on its own to identify each record, such as a table storing Student_ID and Course_ID together, where neither column alone is unique but the combination of both is.

14Textbookcs4-q14

What do you mean by a relationship in DBMS? Explain its types.

Ans.A relationship in DBMS defines how data in one table is connected to data in another table, usually established using primary and foreign keys. Types: (i) One-to-One — each record in one table relates to only one record in another (e.g., a person and their passport). (ii) One-to-Many — one record in a table relates to many records in another (e.g., one teacher teaches many students). (iii) Many-to-Many — records in one table can relate to multiple records in another and vice versa (e.g., students and courses).

Level 1 — Basic

1Textbookcs6-q1

Define a database with one example.

Ans.A database is an organized collection of related data that can be easily accessed, managed, and updated, such as a school's student record system.

2Textbookcs6-q2

What is a field in a database table?

Ans.A field is the smallest unit of data in a table, stored at the place where a row and a column meet, e.g., 'Ram' in the Name column.

3Textbookcs6-q3

Write the syntax to create a database in MySQL.

Ans.CREATE DATABASE database_name;

4Textbookcs6-q4

Which SQL command is used to view all records of a table?

Ans.SELECT * FROM table_name;

Level 2 — Standard

1Textbookcs7-q1

Write an SQL query to create a table named Book with columns BookID (INT, Primary Key), Title (VARCHAR(50)), and Price (DECIMAL(6,2)).

Ans.CREATE TABLE Book ( BookID INT PRIMARY KEY, Title VARCHAR(50), Price DECIMAL(6,2) );

2Textbookcs7-q2

Write an SQL query to insert a record into the Book table with BookID 1, Title 'Science Made Easy', and Price 350.50.

Ans.INSERT INTO Book (BookID, Title, Price) VALUES (1, 'Science Made Easy', 350.50);

3Textbookcs7-q3

Write an SQL query to display the Title and Price of books priced above 300 from the Book table.

Ans.SELECT Title, Price FROM Book WHERE Price > 300;

Level 3 — SEE Style

1Textbookcs8-q1

Differentiate between Primary Key and Foreign Key.

Ans.See table below for the difference between Primary Key and Foreign Key.

2Textbookcs8-q2

Write any four features of DBMS.

Ans.Any four: Data Storage, Easy Data Access, Data Security, Multiple User Support, Data Backup and Recovery, Data Integrity.

3Textbookcs8-q3

Write an SQL query to increase the Price of all books by 50 in the Book table, and another query to delete books whose Price is less than 100.

Ans.UPDATE Book SET Price = Price + 50; DELETE FROM Book WHERE Price < 100;

Level 4 — Application

1Textbookcs9-q1

A school wants to store details of students and their marks in two related tables, Student and Marks. Suggest suitable Primary Key and Foreign Key for these tables and explain why they are needed.

Ans.In the Student table, StudentID can be the Primary Key since it uniquely identifies each student. In the Marks table, Student_ID can be a Foreign Key referring to the Student table's StudentID, so that each mark record is linked to a valid, existing student. These keys are needed to avoid duplicate student records and to ensure that marks are only recorded for students who actually exist in the Student table.

2Textbookcs9-q2

Write an SQL query to display the names of all students from the Student table whose names start with the letter 'S', sorted in ascending order.

Ans.SELECT Name FROM Student WHERE Name LIKE 'S%' ORDER BY Name ASC;

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