Question 1

Question 1Assertion (A): In hierarchical model, searching for a record is a time-consuming task.Reasoning (R): Hierarchical model owns to the organization of information/data in a tree-like structure.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true and R is the correct explanation of A.ExplanationThe hierarchical model arranges data in a tree structure, where each record has a parent-child relationship. Searching for a specific record in such a model may require traversing through multiple levels of the hierarchy, which is time-consuming.

Question 2

Question 3Assertion (A): A database is the largest component for holding and storing data and may contain several tables.Reasoning (R): Each table comprises multiple rows and records.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true and R is the correct explanation of A.ExplanationA database is the largest component for storing and managing data, capable of containing multiple tables. Tables are utilized to organize and store related data in a structured manner, with each table consisting of multiple rows and columns.

Question 3

Question 4Assertion (A): Referential integrity is a constraint that defines rules of holding data in parent and child table.Reasoning (R): Referential integrity ensures that users don't accidently delete or change related data.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true and R is the correct explanation of A.ExplanationReferential integrity is a constraint that defines rules for maintaining data relationships between parent and child tables in a database. The referential integrity constraint requires that values in a foreign key column must either be present in the primary key that is referenced by the foreign key or they must be null. It ensures the preservation of related data by preventing accidental deletion or modification.

Question 4

Question 5Assertion (A): The number of attributes or columns in a relation is called the degree of the relation.Reasoning (R): The number of tuples or records in a relation is called the cardinality of the relation.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true but R is not the correct explanation of A.ExplanationThe degree of a relation and the cardinality of a relation are two separate concepts in database management. The number of attributes or columns in a relation is called the degree of the relation, while the number of tuples or records in a relation is called the cardinality of the relation.

Question 5

Question 6Assertion (A): A foreign key is an attribute whose value is derived from the primary key of another relation.Reasoning (R): A foreign key is used to represent the relationship between tables or relations.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true and R is the correct explanation of A.ExplanationA foreign key is a non-key attribute whose value is derived from the primary key of another table in a database. It references the primary key in another table, thereby establishing a relationship between the two tables.

Question 6

Question 7Assertion (A): Order by clause is used to sort the records of a table in ascending or descending order.Reasoning (R): For sorting in ascending or descending order, ASC and DESC keywords are used along with the Order by clause.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true and R is the correct explanation of A.ExplanationThe SQL ORDER BY clause is used to sort the data is ascending or descending order based on one or more columns. This clause sorts the records in ascending order (ASC) by default. To sort the records in descending order, DESC keyword is used. The syntax for ORDER BY clause is as follows: SELECT FROM [WHERE ] ORDER BY [ASC|DESC];.

Question 7

Question 9Assertion (A): The HAVING clause is used with GROUP BY clause and aggregate functions.Reasoning (R): WHERE clause specifies the condition on individual rows or records.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true but R is not the correct explanation of A.ExplanationThe HAVING clause is used in combination with the GROUP BY clause. It allows aggregate functions to be used along with the specified condition. This is necessary because aggregate functions cannot be used with the WHERE clause, which is evaluated on a single row, whereas aggregate functions are evaluated on a group of rows specified by the GROUP BY clause.

Question 8

Question 11Assertion (A): Cartesian product of two sets (A and B) is defined as the set of all possible ordered pairs denoted by (A + B).Reasoning (R): The Cartesian product is also known as the cross product of two sets. The Cartesian product of two tables can be evaluated such that each row of the first table will be paired with all the rows in the second table.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

A is false but R is true.ExplanationThe Cartesian product of two sets A and B is defined as the set of all possible ordered pairs, denoted as A × B. It is also known as the cross product or cross-join of two sets. In the context of databases, the Cartesian product of two tables can be evaluated such that each row of the first table is paired with all the rows in the second table.

Question 9

Question 13Which of the following types of table constraints will prevent the entry of duplicate rows?UniqueDistinctPrimary KeyNULL

Accepted Answer

Primary KeyReason — A primary key is a set of one or more attributes or fields that uniquely identifies a tuple or row in a table. Therefore, it ensures that each row in the table is unique and prevents the entry of duplicate rows.

Question 10

Question 15Which of the following commands will delete the table from MYSQL database?DELETE TABLEDROP TABLEREMOVE TABLEALTER TABLE

Accepted Answer

DROP TABLEReason — The DROP TABLE command in SQL will delete the table from the MYSQL database. Once this command is executed, the table and all its associated data are removed from the database. After dropping the table, the table name is no longer recognized within the database system, and no further commands can be executed on that object.

Question 11

Question 16Which function is used to display the total number of records from a table in a database?Sum(*)Total(*)Count(*)Return(*)

Accepted Answer

Count(*)Reason — The Count(*) function counts the total number of records/rows satisfying the condition along with NULL values, if any, in the table.

Source: This question is from Relational Database and SQL, Computer Science &mdash; Class 12, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Relational Database and SQL: Question, Display, Total, Number, Records, Table. These are fundamental topics in Computer Science that students are expected to master as part of the CBSE Class 12 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Computer Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach MCQsMultiple choice questions test your ability to quickly recall facts and apply concepts. Read all options carefully before selecting your answer. Use the process of elimination to rule out clearly incorrect options first. If two options seem similar, look for the subtle difference that makes one more accurate. For numerical MCQs, verify your answer by substituting it back into the problem.
Key Points to RememberWrite programs with proper indentation and comments.
Trace through your code with sample inputs to verify correctness.
Explain the logic behind each step of your solution.
Familiarise yourself with common library functions and methods.
Related Questions from Relational Database and SQLQ1: Question 1 Assertion (A): In hierarchical model, searching for a record is a time-consuming task....
Q10: Question 7 Differentiate between DDL and DML commands.
Q11: Question 11 Assertion (A): Cartesian product of two sets (A and B) is defined as the set of all...
Q12: Question 9 An organization wants to create two tables EMP & DEPENDENT to maintain the following...
Q13: Question 13 Which of the following types of table constraints will prevent the entry of duplicate...
Practice more questions from Relational Database and SQL &mdash; Computer Science, Class 12 CBSE

Question 12

Question 17With SQL, how do you select all the records from a table named "Persons", where the value of the column "FirstName" ends with an "a"?SELECT * FROM Persons WHERE FirstName = 'a';SELECT * FROM Persons WHERE FirstName LIKE 'a%';SELECT * FROM Persons WHERE FirstName LIKE '%a';SELECT * FROM Persons WHERE FirstName = '%a%';

Accepted Answer

SELECT * FROM Persons WHERE FirstName LIKE '%a';Reason — The SQL query SELECT * FROM Persons WHERE FirstName LIKE '%a'; retrieves all records from the "Persons" table where the "FirstName" column ends with "a". The LIKE keyword with "%" as a wildcard matches any characters preceding "a".

Question 13

Question 2Write some characteristics of RDBMS.

Accepted Answer

The characteristics of Relational Database Management System (RDBMS) are as follows:Structured Data Storage — RDBMS organizes data into structured tables consisting of rows and columns.Data Integrity — RDBMS enforces data integrity through constraints such as primary keys, foreign keys, unique constraints, and check constraints.Relationships — RDBMS supports relationships between tables.SQL Support — RDBMS uses SQL (Structured Query Language) as the standard language for querying and manipulating data.

Question 14

Question 5What is SQL? What are different categories of commands available in SQL?

Accepted Answer

SQL (Structured Query Language) is a standard language for accessing and manipulating databases.The different categories of SQL commands are as follows:Data Definition Language (DDL) CommandsData Manipulation Language (DML) CommandsData Query Language (DQL) commandData Control Language (DCL) commandsTransaction Control Language (TCL) Commands

Question 15

Question 7Differentiate between DDL and DML commands.

Accepted Answer

Data Definition Language (DDL)Data Manipulation Language (DML)DDL provides a set of definitions to specify the storage structure and access methods used by the database system.DML is a language that enables users to access or manipulate data as organized by the appropriate data model.DDL commands are used to perform tasks such as creating, altering, and dropping schema objects. They are also used to grant and revoke privileges and roles, as well as for maintenance commands related to tables.DML commands are used to retrieve, insert, delete, modify data stored in the database.Examples of DDL commands are CREATE, ALTER, DROP, GRANT, ANALYZE etc.Examples of DML commands are INSERT, UPDATE, DELETE, SELECT etc.

Question 16

Question 9An organization wants to create two tables EMP & DEPENDENT to maintain the following details about its employees and their dependents.EMPLOYEE(AadhaarNumber, Name, Address, Department, EmployeeID)DEPENDENT(EmployeeID, DependentName, Relationship)(a) Name the attributes of EMPLOYEE, which can be used as candidate keys.(b) The company wants to retrieve details of dependents of a particular employee. Name the tables and the key which are required to retrieve these detail.(c) What is the degree of EMPLOYEE and DEPENDENT relation?

Accepted Answer

(a) In the EMPLOYEE table, the attributes AadharNumber and EmployeeID can be used as candidate keys. This means that either AadharNumber or EmployeeID can uniquely identify each record in the EMPLOYEE table.(b) The EMPLOYEE and DEPENDENT tables are linked using the EmployeeID key, which is utilized to retrieve details of dependents associated with a specific employee.(c) In the EMPLOYEE relation, there are five attributes, resulting in a degree of 5. Similarly, the DEPENDENT relation has three attributes, making its degree 3.

Question 17

Question 11Differentiate between char and varchar data types.

Accepted Answer

Char datatypeVarchar datatypeChar datatype specifies a fixed length string.Varchar datatype specifies a variable length string.Defining a length is not required, but the default is 1.Defining a length is required.CHAR(n) ensures that all values stored in that column are of length n bytes, padding shorter values with blanks while maintaining a fixed size of n bytes.VARCHAR(n) columns have a maximum size of n bytes, storing values exactly as specified without adding blanks for shorter lengths. Exceeding n bytes results in an error message.

Question 18

Question 15What is the significance of GROUP BY clause in an SQL query?

Accepted Answer

The GROUP BY clause in SQL can be used in a SELECT statement to collect data across multiple records and group the results by one or more columns. It groups the rows on the basis of the values present in one of the columns and then the aggregate functions are applied on any column of these groups to obtain the result of the query.

Question 19

Question 16What is the difference between WHERE and HAVING clause in SQL select command?

Accepted Answer

The WHERE clause in an SQL SELECT command is used to filter individual rows based on specified conditions, such as column values, before any grouping is performed. On the other hand, the HAVING clause is used for filtering groups of rows after grouping has been applied, with aggregate functions like SUM or AVG.

Question 20

Question 17Write SQL queries to perform the following based on the table PRODUCT having fields as (prod_id, prod_name, quantity, unit_rate, price, city)(i) Display those records from table PRODUCT where prod_id is more than 100.(ii) List records from table PRODUCT where prod_name is 'Almirah'.(iii) List all those records whose price is between 200 and 500.(iv) Display the product names whose price is less than the average of price.(v) Show the total number of records in the table PRODUCT.

Accepted Answer

(i)SELECT * FROM PRODUCT
WHERE prod_id > 100;(ii)SELECT * FROM PRODUCT
WHERE prod_name = 'Almirah';(iii)SELECT * FROM PRODUCT
WHERE price BETWEEN 200 AND 500; (iv)SELECT prod_name
FROM PRODUCT
WHERE price < (SELECT AVG(price) FROM PRODUCT);(v)SELECT COUNT(*) AS total_records FROM PRODUCT;

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