Arts (English Medium) Class 12 - CBSE Question Bank Solutions for Computer Science (Python)

Why is it advised to close a file after we are done with the read and write operations? What will happen if we do not close it? Will some error message be flashed?

What is the difference between the following set of statements (a) and (b):

1. P = open(“practice.txt”,”r”)
   P.read(10)
2. with open(“practice.txt”, “r”) as
   P: x = P.read()

Site any two differences between Single Row Functions and Aggregate Functions.

Write the name of the functions to perform the following operation:

To display the day like “Monday”, and “Tuesday”, from the date when India got independence.

Write the name of the functions to perform the following operation:

To display the specified number of characters from a particular position of the given string.

Write the name of the functions to perform the following operation:

To display the name of the month in which you were born.

Write the name of the functions to perform the following operation:

To display your name in capital letters.

Write the output produced by the following SQL statement:

SELECT ROUND(342.9234, -1);

Write the output produced by the following SQL statement:

SELECT LENGTH("Informatics Practices");

Write the output produced by the following SQL statement:

SELECT    YEAR(“1979/11/26”),
MONTH(“1979/11/26”),    DAY(“1979/11/26”), MONTHNAME(“1979/11/26”);

Write the output produced by the following SQL statement:

SELECT    LEFT("INDIA", 3),    RIGHT("Computer Science", 4),    MID("Informatics", 3, 4), SUBSTR("Practices", 3);

Sahil, a class X student, has just started understanding the basics of Internet and web technologies. He is a bit confused between the terms “World Wide Web” and “Internet”. Help him in understanding both terms with the help of suitable examples of each.

List one advantage and disadvantage of using Cookies.

Which function is used to display the total number of records from a table in a database?

Differentiate between count() and count(*) functions in SQL with appropriate examples.

Write the outputs of the SQL queries based on the relations Teacher and Placement given below:

Table: Teacher

Table: Placement

1. SELECT Department, avg(salary) FROM Teacher GROUP BY Department;
2. SELECT MAX(Date_of_Join), MIN(Date_of_Join) FROM Teacher;
3. SELECT Name, Salary, T.Department, Place FROM Teacher T, Placement P WHERE T.Department = P.Department AND Salary>20000;
4. SELECT Name, Place FROM Teacher T, Placement P WHERE Gender = ’F’ AND T.Department = P.Department;

Predict the output of the code given below:

s="welcome2cs" 

n = len(s)
m=""
for i in range(0, n):
       if (s[i] >= 'a' and s[i] <= 'm'):
            m = m +s[i].upper()
 elif (s[i] >= 'n' and s[i] <= 'z'):
          m = m +s[i-1]
 elif (s[i].isupper()):
     m = m + s[i].lower()
 else:
     m = m +'&'
print(m)

Which function returns the sum of all elements of a list?

Write the use and syntax for the following method:

dump()

Define pickling in Python. Explain serialization and deserialization of Python object.