Learn Python Basics

1. Python
Rafie Tarabay
eng_rafie@mans.edu.eg
mrafie@eg.ibm.com

2. Specify a Variable Type
Casting in python is therefore done using constructor functions:
• int() - constructs an integer number from an integer literal, a float
literal (by rounding down to the previous whole number), or a string
literal (providing the string represents a whole number)
• float() - constructs a float number from an integer literal, a float literal
or a string literal (providing the string represents a float or an integer)
• str() - constructs a string from a wide variety of data types, including
strings, integer literals and float literals

3. Multiline Strings
a = """Lorem ipsum dolor sit amet,
consectetur adipiscing elit,
sed do eiusmod tempor incididunt
ut labore et dolore magna aliqua.""“
print(a)

4. Python Comparison/Assignment Operators

5. Python Collections (Arrays)
There are four collection data types in the Python programming language:
• List [] is a collection which is ordered and changeable. Allows duplicate members.
• Tuple () is a collection which is ordered and unchangeable. Allows duplicate
members.
• Set {} is a collection which is unordered and unindexed. No duplicate members.
• Dictionary {} is a collection which is unordered, changeable and indexed. No
duplicate members.

6. List
thislist=["apple","banana","cherry","orange","kiwi","melon"]
print(thislist[1])
print(thislist[-1])
print(thislist[2:5])
print(thislist[:4])
print(thislist[2:])
thislist[1]="blackcurrant“
print(len(thislist))
forxinthislist:
print(x)
if"apple"inthislist:
print("Yes,'apple'isinthefruitslist")
thislist.append("orange")
thislist.insert(1,"orange")
thislist.remove("banana")
thislist.pop()
delthislist[0]
mylist=thislist.copy()
list3=thislist+mylist

7. SET (Un-Order List)
thisSET={"apple","banana","cherry","orange","kiwi","melon“}
print(thisSET[1])
print(thisSET[-1])
print(thisSET[2:5])
print(thisSET[:4])
print(thisSET[2:])
thisSET[1]="blackcurrant“
print(len(thisSET))
forxinthisSET:
print(x)
if"apple"inthisSET:
print("Yes,'apple'isinthefruitslist")
thisSET.append("orange")
thisSET.add("orange")
thisSET.insert(1,"orange")
thisSET.remove("banana")
thisSET.pop()
delthisSET[0]
mylist=thisSET.copy()
list3=thisSET+mylist
set3=set1.union(set2) #removeduplicate
Red means not valid

8. Tuple (Read-Only List)
thisTuple=("apple","banana","cherry","orange","kiwi","melon“)
print(thisTuple[1])
print(thisTuple[-1])
print(thisTuple[2:5])
print(thisTuple[:4])
print(thisTuple[2:])
thisTuple[1]="blackcurrant“
print(len(thisTuple))
forxin thisTuple:
print(x)
if"apple"in thisTuple:
print("Yes,'apple'isinthefruitstuple")
thisTuple.append("orange")
thisTuple.insert(1,"orange")
thisTuple.remove("banana")
thisTuple.pop()
del thisTuple[0]
mylist=thislist.copy()
tuple3 = tuple1 + tuple2
Red means not valid

9. Dictionary
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
print(thisdict)
x = thisdict["model"]
thisdict["year"] = 2018
print(len(thisdict))
thisdict["color"] = "red“
thisdict.pop("model")
del thisdict["model"]
mydict = thisdict.copy()
for x in thisdict:
print(x) #key
print(thisdict[x]) #value
for x in thisdict.values():
print(x)
for _key , _value in thisdict.items():
print(_key,_value)
if "model" in thisdict:
print("Yes, keys in the dictionary")

10. IF Statement
a= Ture
b=True
If (a and b) :
print (“aaaaaaaaaaaaaaa”)
elif (a or b) :
print (“bbbbbbbbbbbbb”)
elif not(a and b) :
print (“cccccccccccccccc”)
else
print(“ddddddddddddd”)

11. For Statement
for i in range(13):
for j in range(13):
print(str(i)+" X "+str(j)+" = "+str(i*j))
print("=========================")

12. Python Functions
def my_function(fname):
print(fname + " Refsnes")
my_function("Emil")
my_function("Tobias")
def my_func():
print("Hello from a function")
my_func()
def my_function(food):
for x in food:
print(x)
fruits = ["apple", "banana", "cherry"]
my_function(fruits)
def my_function(country = "Norway"):
print("I am from " + country)
my_function("India")
my_function()
my_function("Brazil")
def my_function(x):
return 5 * x
print(my_function(3))
print(my_function(5))

13. Python Functions
def my_function(child3, child2, child1):
print("The youngest child is " + child3)
my_function(child1 = "Emil", child2 = "Tobias", child3 = "Linus")
def tri_recursion(k):
if(k>0):
result = k+tri_recursion(k-1)
print(result)
else:
result = 0
return result
print("nnRecursion Example Results")
tri_recursion(6)
def my_function(*kids):
print("The youngest child is " + kids[2])
my_function("Emil", "Tobias", "Linus")

14. Python Classes and Objects
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
def myfunc(self):
print("Hello my name is " + self.name)
p1 = Person("John", 36)
p1.myfunc()

15. Python Inheritance
class Person:
def __init__(self, fname, lname):
self.firstname = fname
self.lastname = lname
def printname(self):
print(self.firstname, self.lastname)
class Student(Person):
def __init__(self, fname, lname, year):
super().__init__(fname, lname)
self.graduationyear = year
def welcome(self):
print("Welcome", self.firstname, self.lastname, "to the class of", self.graduationyear)
x = Student("Mike", "Olsen", 2019)
x.welcome()

16. Iterable
Lists, tuples, dictionaries, and sets are all iterable objects.
mytuple = ("apple", "banana", "cherry")
myit = iter(mytuple)
print(next(myit))
print(next(myit))
print(next(myit))

17. Python Iterators
class MyNumbers:
def __iter__(self):
self.a = 0
return self
def __next__(self):
self.a += 1
if self.a >100:
raise StopIteration
else:
return self.a
myclass = MyNumbers()
myiter = iter(myclass)
print(next(myiter))
print(next(myiter))

18. Python JSON
import json
# some JSON:
x = '{ "name":"John", "age":30, "city":"New York"}'
# parse x:
y = json.loads(x)
# the result is a Python dictionary:
print(y["age"])

19. convert it into a JSON string
import json
# a Python object (dict):
x = {
"name": "John",
"age": 30,
"city": "New York"
}
# convert into JSON:
y = json.dumps(x)
# the result is a JSON string:
print(y)

20. Python Try Except
try:
f = open("demofile.txt")
f.write("Lorum Ipsum")
except:
print("Something went wrong when writing to the file")
finally:
f.close()

21. Python User Input
username = input("Enter username:")
print("Username is: " + username)

22. File Handling
f = open("demofile.txt", "rt")
print(f.read()) #read All Lines
for one_Line in f:
print(one_Line)
f.close()
############################
f1 = open("demofile2.txt", "a")
f1.write("Now content!")
f1.close()
############################
import os
if os.path.exists("demofile.txt"):
os.remove("demofile.txt")
os.rmdir("myfolder")

23. Python Requests Module
import requests
x = requests.get('https://w3schools.com/python/demopage.htm')
print(x.text)

24. Python MySQL
Download a free MySQL database at
https://dev.mysql.com/downloads/mysql/5.5.html
Download and install "MySQL Connector":
python -m pip install mysql-connector

25. SQL Commands

26. Database Table
Here is a Sample DB table with name “Customers”

27. CREATE TABLE
• CREATE TABLE table_name (
column1 datatype,
column2 datatype,
column3 datatype,
....
);
• CREATE TABLE Persons (
PersonID int,
LastName varchar(255),
FirstName varchar(255),
Address varchar(255),
City varchar(255)
);

28. INSERT INTO Statement
• INSERT INTO table_name (column1, column2, column3, ...)
VALUES (value1, value2, value3, ...);
• INSERT INTO table_name
VALUES (value1, value2, value3, ...);

29. SQL SELECT Statement
• SELECT column1, column2, ...
FROM table_name;
• SELECT * FROM table_name;
• SELECT DISTINCT column1, column2, ...
FROM table_name;
• SELECT COUNT(DISTINCT Country) FROM Customers;

30. SQL WHERE Clause
• SELECT column1, column2, ...
FROM table_name
WHERE condition;
• SELECT * FROM Customers
WHERE Country='Mexico’;
• SELECT * FROM Customers
WHERE CustomerID=1;

31. Operators in The WHERE Clause

32. SQL AND, OR and NOT Operators
• SELECT column1, column2, ...
FROM table_name
WHERE condition1 AND condition2 AND condition3 ...;
• SELECT column1, column2, ...
FROM table_name
WHERE condition1 OR condition2 OR condition3 ...;
• SELECT column1, column2, ...
FROM table_name
WHERE NOT condition;

33. SQL AND, OR and NOT Operators
• SELECT * FROM Customers
WHERE Country='Germany' AND City='Berlin';
• SELECT * FROM Customers
WHERE City='Berlin' OR City='München';
• SELECT * FROM Customers
WHERE NOT Country='Germany';

34. Combining AND, OR and NOT
• SELECT * FROM Customers
WHERE Country='Germany' AND (City='Berlin' OR City='München’);
• SELECT * FROM Customers
WHERE NOT Country='Germany' AND NOT Country='USA';

35. SQL ORDER BY Keyword
• SELECT column1, column2, ...
FROM table_name
ORDER BY column1, column2, ... ASC|DESC;
• SELECT * FROM Customers
ORDER BY Country;
• SELECT * FROM Customers
ORDER BY Country DESC;
• SELECT * FROM Customers
ORDER BY Country, CustomerName;
• SELECT * FROM Customers
ORDER BY Country ASC, CustomerName DESC;

36. UPDATE Statement
• UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;
• UPDATE Customers
SET ContactName = 'Alfred Schmidt', City= 'Frankfurt'
WHERE CustomerID = 1;
• UPDATE Customers
SET ContactName='Juan'
WHERE Country='Mexico';

37. DELETE Statement
• DELETE FROM table_name;
• DELETE FROM table_name WHERE condition;
• DELETE FROM Customers WHERE CustomerName='Alfreds
Futterkiste';

38. MIN() and MAX() Functions
• SELECT MIN(column_name)
FROM table_name
WHERE condition;
• SELECT MAX(column_name)
FROM table_name
WHERE condition;
• SELECT MIN(Price) AS SmallestPrice
FROM Products;
• SELECT MAX(Price) AS LargestPrice
FROM Products;

39. COUNT(), AVG() and SUM()
• SELECT COUNT(ProductID)
FROM Products;
• SELECT AVG(Price)
FROM Products;
• SELECT SUM(Quantity)
FROM OrderDetails;

40. LIKE Operator
wildcards for LIKE operator:
• % The percent sign represents zero, one, or multiple characters
• _ The underscore represents a single character
• SELECT column1, column2, ...
FROM table_name
WHERE column LIKE pattern;
• SELECT * FROM Customers
WHERE City LIKE 'ber%';
• SELECT * FROM Customers WHERE City LIKE '%es%’;
• SELECT * FROM Customers WHERE City LIKE '_ondon';

41. IN Operator
• SELECT column_name(s)
FROM table_name
WHERE column_name IN (value1, value2, ...);
• SELECT column_name(s)
FROM table_name
WHERE column_name IN (SELECT STATEMENT);
• SELECT * FROM Customers
WHERE Country IN ('Germany', 'France', 'UK’);
• SELECT * FROM Customers
WHERE Country IN (SELECT Country FROM Suppliers);

42. BETWEEN Operator
• SELECT column_name(s)
FROM table_name
WHERE column_name BETWEEN value1 AND value2;
• SELECT * FROM Products
WHERE Price BETWEEN 10 AND 20;
• SELECT * FROM Products
WHERE Price NOT BETWEEN 10 AND 20;

43. Python MySQL
Handel DB from Python

44. Python Mysql Connection
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="yourusername",
passwd="yourpassword"
)
mycursor = mydb.cursor()
mycursor.execute("CREATE DATABASE mydatabase")
mycursor.execute("SHOW DATABASES")
for x in mycursor:
print(x)
mycursor.execute("CREATE TABLE mydatabase .customers (name VARCHAR(255), address VARCHAR(255))")

45. Mysql Insert
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="yourusername",
passwd="yourpassword",
database="mydatabase"
)
mycursor = mydb.cursor()
sql = "INSERT INTO customers (name, address) VALUES (%s, %s)"
val = ("John", "Highway 21")
mycursor.execute(sql, val)
mydb.commit()
print(mycursor.rowcount, "record inserted.")

46. Python MySQL Select From
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="yourusername",
passwd="yourpassword",
database="mydatabase"
)
mycursor = mydb.cursor()
mycursor.execute("SELECT * FROM customers")
myresult = mycursor.fetchall()
for x in myresult:
print(x)

47. Python MySQL Update From
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="yourusername",
passwd="yourpassword",
database="mydatabase"
)
mycursor = mydb.cursor()
sql = "UPDATE customers SET address = %s WHERE address = %s"
val = ("Valley 345", "Canyon 123")
mycursor.execute(sql, val)
mydb.commit()
print(mycursor.rowcount, "record(s) affected")