4.Python MySQL

Before diving deep, let's understand

What is MySQL?

MySQL is an Open-Source database and one of the best type of RDBMS (Relational Database Management System). Co-founder of MySQLdb is Michael Widenius's, and also MySQL name derives from the daughter of Michael.

How to Install MySQL

Install MySQL in Linux/Unix:

Download RPM package for Linux/Unix from Official site: https://www.mysql.com/downloads/

In terminal use following command

rpm  -i <Package_name>

Example   rpm -i MySQL-5.0.9.0.i386.rpm
         

To check in Linux

mysql --version

Install MySQL in Windows

Download MySQL database exe from official site and install as usual normal installation of software in Windows. Refer this tutorial, for a step by step guide

Install MySQL Connector Library for Python

For Python 2.7 or lower install using pip as:

pip install mysql-connector
         

For Python 3 or higher version install using pip3 as:

pip3 install mysql-connector 

Test the MySQL Database connection with Python

To test database connection here we use pre-installed MySQL connector and pass credentials into connect() function like host, username and password.

Syntax to access MySQL with Python:

             import mysql.connector
             db_connection = mysql.connector.connect(
               host="hostname",
               user="username",
               passwd="password"
             )
         

Example,

         import mysql.connector
         db_connection = mysql.connector.connect(
           host="localhost",
           user="root",
           passwd="root"
         )
         print(db_connection)
         

Output:

<mysql.connector.connection.MySQLConnection object at 0x000002338A4C6B00>

Here output shows the connection created successfully.

Creating Database in MySQL using Python

Syntax to Create new database in SQL is

CREATE DATABASE "database_name"
         

Now we create database using Python in MySQL

           import mysql.connector
           db_connection = mysql.connector.connect(
           host= "localhost",
           user= "root",
           passwd= "root"
           )
         # creating database_cursor to perform SQL operation
         db_cursor = db_connection.cursor()
         # executing cursor with execute method and pass SQL query
         db_cursor.execute("CREATE DATABASE my_first_db")
         # get list of all databases
         db_cursor.execute("SHOW DATABASES")
         #print all databases
         for db in db_cursor:
             print(db)
         

Output:

Here above image shows the my_first_db database is created

Create a Table in MySQL with Python

Let's create a simple table "student" which has two columns.

SQL Syntax:

CREATE  TABLE student (id INT, name VARCHAR(255))
         

Example:

           import mysql.connector
           db_connection = mysql.connector.connect(
           host="localhost",
           user="root",
           passwd="root",
           database="my_first_db"
           )
         db_cursor = db_connection.cursor()
         #Here creating database table as student'
         db_cursor.execute("CREATE TABLE student (id INT, name VARCHAR(255))")
         #Get database table'
         db_cursor.execute("SHOW TABLES")
         for table in db_cursor:
             print(table)
         

Output:

 ('student',) 

Create a Table with Primary Key

Let's create an Employee table with three different columns. We will add a primary key in id column with AUTO_INCREMENT constraint

SQL Syntax,

CREATE TABLE employee(id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(255), salary INT(6))
         

Example,

           import mysql.connector
           db_connection = mysql.connector.connect(
           host="localhost",
           user="root",
           passwd="root",
           database="my_first_db"
           )
         db_cursor = db_connection.cursor()
         #Here creating database table as employee with primary key
         db_cursor.execute("CREATE TABLE employee(id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(255), salary INT(6))")
         #Get database table
         db_cursor.execute("SHOW TABLES")
         for table in db_cursor:
             print(table)	
         

Output:

('employee',) ('student',)

ALTER table in MySQL with Python

Alter command is used for modification of Table structure in SQL. Here we will alter Student table and add a primary key to the id field.

SQL Syntax,

ALTER TABLE student MODIFY id INT PRIMARY KEY
         

Example,

           import mysql.connector
           db_connection = mysql.connector.connect(
           host="localhost",
           user="root",
           passwd="root",
           database="my_first_db"
           )
         db_cursor = db_connection.cursor()
         #Here we modify existing column id
         db_cursor.execute("ALTER TABLE student MODIFY id INT PRIMARY KEY")
         

Output:

Here below you can see the id column is modified.

Insert Operation with MySQL in Python:

Let's perform insertion operation in MySQL Database table which we already create. We will insert data oi STUDENT table and EMPLOYEE table.

SQL Syntax,

         INSERT INTO student (id, name) VALUES (01, "John")
         INSERT INTO employee (id, name, salary) VALUES(01, "John", 10000)
         

Example,

           import mysql.connector
           db_connection = mysql.connector.connect(
           host="localhost",
           user="root",
           passwd="root",
           database="my_first_db"
           )
         db_cursor = db_connection.cursor()
         student_sql_query = "INSERT INTO student(id,name) VALUES(01, 'John')"
         employee_sql_query = " INSERT INTO employee (id, name, salary) VALUES (01, 'John', 10000)"
         #Execute cursor and pass query as well as student data
         db_cursor.execute(student_sql_query)
         #Execute cursor and pass query of employee and data of employee
             db_cursor.execute(employee_sql_query)
         db_connection.commit()
         print(db_cursor.rowcount, "Record Inserted")
         

Output:

 2 Record Inserted