Commerce (English Medium) Class 12 - CBSE Question Bank Solutions

Write a short note on different methods of malware identification used by antivirus software.

______ command is used to remove the primary key from a table in SQL.

Which of the following commands will delete the table from the MYSQL database?

______ is a non-key attribute, whose values are derived from the primary key of some other table.

To establish a connection between Python and SQL databases, connect() is used. Which of the following arguments may not necessarily be given while calling connect()?

Write the command to view all tables in a database.

The code given below reads the following record from the table named student and displays only those records that have marks greater than 75:

• RollNo - integer
• Name - string
• Clas - integer
• Marks - integer

Note the following to establish connectivity between Python and MYSQL:

• Username is root.
• The password is the tiger.
• The table exists in an MYSQL database named school.

Write the following missing statements to complete the code:

Statement 1 - to form the cursor object
Statement 2 - to execute the query that extracts records of those students whose marks are greater than 75.
Statement 3 - to read the complete result of the query (records whose marks are greater than 75) into the object named data, from the table student in the database.

import mysql.connector as mysql
def sql_data():
       con1=mysql.connect(host="localhost",user="root",password="tiger", database="school")
       mycursor=_______________ #Statement 1
       print("Students with marks greater than 75 are :")
                  _________________________ #Statement 2
                 data=__________________ #Statement 3
                for i in data:
                   print(i)
                print()

Navdeep creates a table RESULT with a set of records to maintain the marks secured by students in Sem1, Sem2, Sem3, and their divisions. After the creation of the table, he entered data of 7 students in the table.

Based on the data given above answer the following questions:

1. Identify the most appropriate column, which can be considered as the Primary key.
2. If two columns are added and 2 rows are deleted from the table result, what will be the new degree and cardinality of the above table?
3. Write the statements to:
   a. Insert the following record into the table
   Roll No - 108, Name - Aadit, Sem1- 470, Sem2 - 444, Sem3 - 475, Div - I.
   b. Increase the SEM2 marks of the students 3% whose name begins with ‘N’.
   OR
   Write the statements to:
   a. Delete the record of students securing IV division.
   b. Add a column REMARKS in the table with datatype as varchar with 50 characters.

Write the command to view all databases.

Name any two DDL commands.

The code given below deletes the record from the table employee, which contains the following record structure:

E_code - String
E_name - String
Sal - Integer
City - String

Note the following to establish connectivity between Python and MySQL:

• Username is root
• Password is root
• The table exists in a MySQL database named emp.
• The details (E_code, E_name, Sal, City) are the attributes of the table.

Write the following statements to complete the code:

Statement 1 – to import the desired library.

Statement 2 – to execute the command that deletes the record with E_code as 'E101'.

Statement 3 – to delete the record permanently from the database. ____________

import ____________ as mysql #Statement1
def delete():
      mydb=mysql.connect(host="localhost",use r="root", 
      passwd="root",database="emp")

mycursor=mydb.cursor()
____________ #Statement 2
____________ #Statement 3
print ("Record deleted") 

An exception may be raised even if the program is syntactically correct.

Ms Shalini has just created a table named “Employee” containing columns Ename, Department and Salary. After creating the table, she realized that she has forgotten to add a primary key column in the table. Help her in writing an SQL command to add a primary key column EmpId of integer type to the table Employee.

Thereafter, write the command to insert the following record in the table:

EmpId- 999
Ename- Shweta
Department: Production
Salary: 26900

Consider the table Personal given below:

Based on the given table, write SQL queries for the following:

1. Increase the salary by 5% of personals whose allowance is known.
2. Display Name and Total Salary (sum of Salary and Allowance) of all personals. The column heading ‘Total Salary’ should also be displayed.
3. Delete the record of Supervisors who have salary greater than 25000.

Define the term bandwidth with respect to networks.

Hi-Standard Tech Traj.ning Ltd. is a Mumbai based organization which is expanding its office set-up to Chennai. At Chennai office compound, they are planning to have 3 different blocks for Admin, Training and Accounts related activities. Each block has a number of computers, which are required to be connected in a network for communication, data and resource sharing.

As a network consultant, you have to suggest the best network related solutions for them for issues/problems raised by them in (i) to (iv), as per the distances between various blocks/locations and other given parameters.

Shortest differences between various blocks/locations:

The number of computers installed at various blocks is as follows:

1) Suggest the most appropriate block/location to house the SERVER in the CHENNAI office (out of the 3 blocks) to get the best and effective connectivity. Justify your answer.

2) Suggest the best-wired medium and draw the cable layout (Block to Block) to efficiently connect various blocks within the CHENNAI office compound.

3) Suggest a device/software and its placement that would provide data security for the entire network of the CHENNAI office.

4) Suggest a device and the protocol that shall be needed to provide wireless Internet access to all smartphone/laptop users in the CHENNAI office

Differentiate between packet switching over message switching

When are the following built-in exceptions raised? Give examples to support your answer.

ImportError

When are the following built-in exceptions raised? Give examples to support your answer.

IOError

When are the following built-in exceptions raised? Give examples to support your answer.

NameError