If a column of a table is declared to be an INTEGER PRIMARY KEY, then whenever a NULL is used as an input for this column, the NULL will be automatically converted into an integer which will be one larger than the highest value so far used in that column.

Modular programming is a software design technique to split our code into separate parts. These parts are called modules. The focus for this separation should have modules with no or just few dependencies upon other modules.

Data Consistency means that data values are the same at all instances of a database.

(i) Subroutines are the basic building blocks of computer programs. Subroutines are small sections of code that are used to perform a particular task that can be used repeatedly.
(ii) In Programming languages these subroutines are called as Functions.

Variables defined inside a class are called as "Class Variable" and functions are called as "Methods. Class variable and methods are together known as members of the class. The class members should be accessed through objects or instance of class. A class can be defined anywhere in a Python program.
Defining classes: In Python, a class is defined by using the keyword class. Every class has a unique name followed by a colon (:).
Syntax for Defining a Class:
class class_name:
statement_1
statement_2
....................
....................
statement_n

Str 1 = "COMPUTER"
index = 0
for i in str 1:
print (str 1[:index -1])
index =1

(i) Ternary operator is also known as conditional operator that evaluate something based on a condition being true or false.
(ii) It simply allows testing a condition in a single line replacing the multiline if-else making the code compact. The syntax for conditional operator is,
Variable Name = [on_true] if [Test expression]
else [on_false]
(iii) Example:
min = 50 if 49 < 50 else 70 # min = 50
min = 50 if 49 > 50 else 70 # min = 70

(i) Access control is a security technique that regulates who or what can view or use resources in a computing environment.
(ii) It is a fundamental concept in security that minimizes risk to the object.
(iii) In other words access control is a selective restriction of access to data.
(iv) In object oriented programming languages is implemented through access modifiers.

Line Chart:
(i) A Line Chart or Line Graph is a type of chart which displays information as a series of data points called 'markers' connected by straight line segments.
(ii) A Line Chart is often used to visualize a trend in data over intervals of time - a time series - thus the line is often drawn chronologically.
Example:
import matplotlib.pyplot as plt
years = [2014, 2015, 2016, 2017, 2018]
total_populations = [8939007, 8954518, 8960387, 8956741, 8943721]
plt. plot ("years, total_populations)
pit. title ("Year vs Population in India")
plt.xlabel ("Year")
pIt.ylabel ("Total Population")
plt.showt (1)
In this program,
Plt.titlet( ) \(\rightarrow\) specifies title to the graph
Plt.xlabelt) \(\rightarrow\) specifies label for X-axis
Plt.ylabel() \(\rightarrow\) specifies label for Y-axis
Output:

Bar Chart:
(i) A Bar Plot (or BarChart) is one of the most common type of plot. It shows the relationship between a numerical variable and a categorical variable
(ii) Bar chart represents categorical data with rectangular bars. Each bar has a height corresponds to the value it represents. The bars can be plotted vertically or horizontally.
(iii) It's useful when we want to compare a given numeric value on different categories. To make a bar chart with Matplotlib, we can use the plt.bar() function.
Example:
import matplotlib.pyplot as plt
# Our data
labels = ["TAMIL", "ENGLISH", "MATHS", "PHYSICS", "CHEMISTRY", "CS"]
usage = [79.8,67.3,77.8,68.4,70.2,88.5]
# Generating the y positions. 
y_positions = range (len(labels))
# Creating our bar plot
plt.bar (y_positions, usage)
plt.xticks (y_positions, labels)
plt.ylabel ("RANGE")
plt.title ("MARKS")
plt.show( )
Output:

Labels → specifies labels for the bars.
Usage → Assign values to the labels specified.
Xticks → Display the tick marks along the x - axis at the values represented. Then specify the ladel for each tick mark.
Range → Create sequence of numbers.
Pie Chart:
(i) Pie Chart is probably one of the most common type of chart. It is a circular graphic which is divided into slices to illustrate numerical proportion.
(ii) The point of a pie chart is to show the relationship of parts out of a whole. To make a Pie Chart with Matplotlib, we can use the plt.pief) function.
(iii) The autopct parameter allows us to display the percentage value using the Python string formatting.
Example:
import matplotlib.pyplot as plt
sizes = [89, 80, 90, 100, 75]
labels = ["Tamil", "English", "Maths", "Science", "Social"]
plt.pie (sizes, labels = labels, autopct = "%.2f")
plt.axes().set aspect ("equal")
plt.show( )
Output:

In Python, a tuple can be defined inside another tuple; called Nested tuple. In a nested tuple, each tuple is considered as an element. The for loop will be useful to access all the elements in a nested tuple.
Example:
Toppers = (("Vinodini", "XII-F", 98.7), ("Soundarya", "XII-H", 97.5),
("Tharani", "XII-F", 95.3), ("Saisri", "XII-G", 93.8))
for i in Toppers:
print(i)
Output:
('Vinodini', 'XII-F', 98.7)
('Soundarya', 'XII-H', 97.5)
('Tharani', 'XII-F', 95.3)
('Saisri', 'XII-G', 93.8)

String Operators:
Python provides the following operators for string operations. These operators are useful to manipulate string.
(i) Concatenation (+):
Joining of two or more strings is called as Concatenation. The plus (+) operator is used to concatenate strings in python.
Example:
>>> "welcome" + "Python"
'welcome python'
(ii) Append (+ =):
Adding more strings at the end of an existing string is known as append. The operator += is used to append a new string with an existing string.
Example:
>>> str1 = "welcome to"
>>> str1 + = "Learn Python"
>>> print (str1)
Welcome to Learn Python
(iii) Repeating (*):
The multiplication operator (*) is used to display a string in multiple number of times.
Example:
>>> str1= "welcome "
>>> print (str1 *4)
Welcome Welcome Welcome Welcome
(iv) String slicing:
Slice is a substring of a main string.
A substring can be taken from the original string by using [ ] operator and index or subscript values. Thus [ ] is also known as slicing operator. Using slice operator, we have to slice one or more substrings from a main string.
General format of slice operation:
str[start:end]
Where start is the beginning index and end is the last index value of a character in the string. Python takes the end value less than one from the actual index specified.
Example: I
Slice a single character from a string
>>>str 1 = "THIRUKKURAL"
>>>print (str 1 [0])
       T
(v) Stride when slicing string:

• When the slicing operator, we can specify a third argument as the stride, which refers to the number of characters to move forward after the first character is retrieved from the string.
• The default  value of stride is 1
• Python takes the last value as n-1
• We can also use negative value stride, to print data in reverse order.

Example :
>>>str1 = "Welcome to learn python"
>>>print(str1[::-2])
Output :
nhy re teolW

The following are the desirable characteristics of a module.
(i) Modules contain instructions, processing logic, and data.
(ii) Modules can be separately compiled and stored in a library.
(iii) Modules can be included in a program.
(iv) Module segments can be used by invoking a name and some parameters.
(v) Module segments can be used by other modules.

Pure functions:
(i) Pure functions are functions which will give exact result when the same arguments are passed.
(ii) For example the mathematical function sin (0) always results 0. This means that every time you call the function with the same arguments, you wil always get the same result.
(iii) A function can be a pure function provided it should not have any external variable which will alter the behavior of that variable.
let us see an Example:
Let square x : =
            return: x * x
(iv) The above function square is a pure function because it will not give different results for same input.
(v) There are various theoretical advantages of having pure functions. One advantage is that if a function is pure, then if it is called several times with the same arguments, the compiler only needs to actually call the function once.
Example:
let length s:=
     i:= 0
     let i:= 0;
     if i<strlen (s) then
     -- Do something which doesn't affect s
     ++1
(vi) If it is compiled, strlen (s) is called each time and strlen needs to iterate over the whole of 's'. If the compiler is smart enough to work out that strlen is a pure function and that 's' is not updated in the loop, then it can remove the redundant extra calls to strlen and make the loop to execute only one time.
(vii) From these what we can understand, strlen is a pure function because the function takes one variable as a parameter, and accesses it to find its length. This function reads external memory but does not change it, and the value returned derives from the external memory accessed
Impure functions:
(i) The variables used inside the function may cause side effects through the functions which are not passed with any arguments. In which cases the function is called impure function.
(ii) When a function depends on variable or functions outside of its definition block, you can never be sure that the function will behave the same every time it's called. For example, the mathematical functions random ( ) will give different outputs for the same function call.
Example:
let randomnumber:=
      a := random()
          if a > 10 then
            return: a
  else
            return: 10
(iii) Here the function Random is impure as it is not sure what will be the result when we call the function