Python DB API allows Python applications to interact with relational databases in a uniform way. It supports various databases including SQLite, MySQL, PostgreSQL, Oracle, and SQL Server. The document discusses connecting Python to MySQL, executing SQL queries, and fetching data. It provides code to connect to a MySQL database, create a table, insert sample data, run queries, and display results.

1. Python DB API
Prepared By : Dhara Wagh

2. Outline
• Definition of Python DB-API
• Python supported databases
• Brief of MySQL
• Prerequisites
• How to connect python with MySQL DB
• Steps to setting up & method to execute MySQL in Python
• Execution of Demo Program

3. Definition of Python DB-API
• Python Database API (DB-API) is a standardized interface that enables
interactions between Python applications and relational databases.
• It serves as a specification for accessing various database systems in a
uniform manner from Python.
• Python DB-API facilitates essential operations, including connecting to
databases, executing SQL queries, and managing data.

4. Compatibility with various database
management systems
1. SQLite: A lightweight, self-contained, and serverless database engine.
2.MySQL: A popular open-source relational database management system.
3.PostgreSQL: A powerful, open-source object-relational database system known for its
robust features.
4.Oracle: A widely used enterprise-level relational database management system.
5.Microsoft SQL Server: A comprehensive and feature-rich database system developed
by Microsoft.
6.NoSQL Databases: Certain Python DB-API implementations extend support to
NoSQL databases like MongoDB, enabling interaction with non-tabular data models.

5. Brief introduction to MySQL
• MySQL is an open-source relational database management system
that is widely used for various applications, ranging from small-
scale to large-scale enterprises. It is known for its speed, reliability,
and ease of use, making it a popular choice for many developers
and organizations.

6. Prerequisites to work with Python and MySQL
1. Python: Ensure that you have Python installed on your system.
You can download the latest version of Python from the official
website: https://www.python.org/downloads/
2. MySQL Database: You need to have MySQL installed on your
machine or have access to a remote MySQL server. You can
download MySQL from the official website:
https://www.mysql.com/downloads/

7. Installing the required Python libraries
• To interact with MySQL in Python, you need to install the 'mysql-connector-python' library.
• Use the following command to install it: pip install mysql-connector-python
• Configuring MySQL connection parameters
• You need to specify the host, user, password, and database name to establish a connection
with MySQL.
• For example: Host: "localhost" (if the MySQL server is on the same machine)
User: "yourusername"
Password: "yourpassword"
Database: "yourdatabase"

8. How to connect python with MySQL DB

9. • The DB API provides a minimal standard for working with databases using
Python structures and syntax wherever possible. This API includes the
following −
• Importing the API module.
• Acquiring a connection with the database.
• Issuing SQL statements and execute .
• Closing the connection

10. Setting up MySQL in Python
• Installing and importing the required Python libraries
• Configuring MySQL connection parameters
• Demonstrating how to establish a connection

11. Importing the Different DB API Module
• # Importing the MySQL DB API module
import mysql.connector
• # Importing the PostgreSQL DB API module
import psycopg2
• # Importing the SQLite DB API module
import sqlite3

12. Connecting in Python DB-API
• Use the connect() method provided by the specific Python DB-API module to
establish a connection to the desired database.
• Define the necessary connection parameters such as the database's address,
username, password, and other relevant details within the connect() method.
• Upon successful execution, the Python program gains the capability to send and
receive data from the connected database, paving the way for data retrieval,
modification, and more.

13. Create a connection in Python:
import mysql.connector
mydb = mysql.connector.connect( host="localhost",
user="yourusername“,
password="yourpassword",
database="yourdatabase“ )
**Ensure that the values for host, user, password, and database match the
credentials and details of your MySQL server.

14. Interacting with the Database
• Create Cursor object and executing SQL queries using Python
• Fetching data from MySQL
• Displaying the results in Python

15. Creating cursor object
• We need to create the object of a class called cursor that allows Python code to
execute database command in a database session
• After establishing the connection, you can execute SQL queries using the cursor
object.
Mysql / PostgreSql
cursorobj = db.cursor( )
• For example : mycursor = mydb.cursor()

16. Executing SQL queries using Python
We can execute the sql queries from python program using execute() method
associated with cursor object.
Examples:
mycursor.execute("SELECT * FROM yourtable")
mycursor.execute(“SELECT * from tbl _student”)
mycursor.éxecute("select a from tbl where b=? and c-?”, x, y)
mycursor execute("select a from tbl where b=? and c=?", (х, y))

17. Execute SOL query
• Executes an SQL. command against all parameter sequences or mappings found in the sequence sq
sql = "INSERT INTO customer (name, address) VALUES (%s, %s)"
val = [
("John Doe", "123 Street, City"),
("Jane Smith", "456 Avenue, Town"),
("Michael Johnson", "789 Road, Village"),
("Sarah Williams", "101 Main Street, Country")
]
mycursor.executemany(sql, val)

18. Fetch data from MySQL
• MySQL provides multiple ways to retrieve data such as
fetchall() : Fetch all (remaining) rows of a query result, returning them as a
sequence of sequences (eg, a list of tuples).
fetchmany(size) : Fetch the next set of rows of a query result, returning a
sequence of sequences (c.g. a list of tuples) It will return number of rows that
matches to the size argument
fetchone() : Fetch the next row of a query result set, returning a single
sequence, or None when no more data is available

19. Fetching data from MySQL
• Use the fetchall() method to retrieve the data resulting from the executed
query.
• Assign the fetched data to a variable for further processing.
• For example: result = mycursor.fetchall()

20. Execute fetch data query
● # Assuming mycursor is the cursor object after executing a query
● mycursor.execute("SELECT * FROM yourtable")
● # Using the fetchall() method to fetch all rows from the result set :
result = mycursor.fetchall()
for row in result:
print(row)
● # Using the fetchone() method to fetch one row at a time from the result set
mycursor.execute("SELECT * FROM yourtable WHERE id = 1")
result = mycursor.fetchone()
print(result)
● # Using the fetchmany() method to fetch a specific number of rows from the result set
mycursor.execute("SELECT * FROM yourtable")
result = mycursor.fetchmany(5)
for row in result:
print(row)

21. Displaying the results in Python
• Utilize Python's print function to display the fetched data or process it
further according to the requirements.
• For instance:
for x in result:
print(x)
This will print each row retrieved from the MySQL database, based on the
executed query.

22. Demo Program
import mysql.connector
# Establishing a connection
mydb = mysql.connector.connect( host="localhost",user="root", password="admin“ )
# Creating a cursor object
mycursor = mydb.cursor()
# Creating a database
mycursor.execute("CREATE DATABASE if not exists mydbtest")
print("Database created successfully.")
# Using the created database
mycursor.execute("USE mydbtest")
print("database created successfully.")

23. Demo Program CONTINUE..
# Creating a table
mycursor.execute("CREATE TABLE if not exists customers (id INT AUTO_INCREMENT
PRIMARY KEY, name VARCHAR(255), address VARCHAR(255))")
# Inserting data into the table
sql = "INSERT INTO customers (name, address) VALUES (%s, %s)"
val = [
("John Doe", "123 Street, City"),
("Jane Smith", "456 Avenue, Town"),
("Michael Johnson", "789 Road, Village"),
("Sarah Williams", "101 Main Street, Country")
]
mycursor.executemany(sql, val)
# Committing the changes
mydb.commit()
print(mycursor.rowcount, "record inserted.")

24. Demo Program CONTINUE..
#displaying data using select
mycursor.execute("SELECT * FROM customers")
# Fetching the data
result = mycursor.fetchall()
# Displaying the data
for x in result:
print(x)
# Dropping the table
mycursor.execute("DROP TABLE IF EXISTS customers")
print("Table 'customers' deleted successfully.")
# Closing the connection
mydb.close()
print("Connection closed.")

25. Output :

26. References
• List of resources for further learning:
1.Python MySQL Database Access - Official Documentation:
https://dev.mysql.com/doc/connector-python/en/
2.W3Schools Python MySQL Tutorial:
https://www.w3schools.com/python/python_mysql_getstarted.asp
3.Real Python - Working with MySQL Databases using Python:
https://realpython.com/python-mysql/

27. Links to relevant tutorials:
• Python MySQL Connector Documentation:
https://dev.mysql.com/doc/connector-python/en/
• MySQL Documentation: https://dev.mysql.com/doc/
• Python Official Documentation: https://docs.python.org/3/
• MySQL Tutorial on w3schools:
https://www.w3schools.com/python/python_mysql_getstarted.asp
• Real Python's Tutorial on Python MySQL: https://realpython.com/python-mysql/

28. Any Questions??

29. Thank You