Python MySQL: Delete Query

Introduction

The DELETE statement in SQL is used to remove one or more records from a table. Python, with its extensive library support, makes it easy to interact with MySQL databases and execute SQL queries. In this guide, we will use the mysql-connector-python library to execute DELETE queries and remove data from a MySQL table.

Setting Up

Install MySQL Connector

First, you need to install the MySQL connector for Python. You can install it using pip:

pip install mysql-connector-python

Connecting to MySQL

To delete data from a table, you need to connect to the MySQL server and the specific database where the table is located. You will need the following details:

• Hostname (usually localhost)
• Username
• Password
• Database name

Example: Connecting to MySQL

import mysql.connector

# Connect to the MySQL server and database
connection = mysql.connector.connect(
    host="localhost",
    user="your_username",
    password="your_password",
    database="your_database"
)

if connection.is_connected():
    print("Connected to MySQL database")

# Close the connection
connection.close()

Deleting Data

Once you have connected to the MySQL database, you can delete data from a table by executing a DELETE statement using a cursor object.

Example: Deleting Data

import mysql.connector

# Connect to the MySQL server and database
connection = mysql.connector.connect(
    host="localhost",
    user="your_username",
    password="your_password",
    database="your_database"
)

# Create a cursor object
cursor = connection.cursor()

# Execute a DELETE query
delete_query = "DELETE FROM employees WHERE id = %s"
data = (1,)
cursor.execute(delete_query, data)

# Commit the transaction
connection.commit()
print("Record deleted successfully")

# Close the connection
connection.close()

Deleting Multiple Rows

You can delete multiple rows by specifying a condition that matches multiple records.

Example: Deleting Multiple Rows

import mysql.connector

# Connect to the MySQL server and database
connection = mysql.connector.connect(
    host="localhost",
    user="your_username",
    password="your_password",
    database="your_database"
)

# Create a cursor object
cursor = connection.cursor()

# Execute a DELETE query to delete multiple rows
delete_query = "DELETE FROM employees WHERE age > %s"
data = (30,)
cursor.execute(delete_query, data)

# Commit the transaction
connection.commit()
print(cursor.rowcount, "record(s) deleted")

# Close the connection
connection.close()

Handling Exceptions

It’s important to handle exceptions that might occur during the database operations to ensure that your program can handle errors gracefully.

Example: Handling Exceptions

import mysql.connector
from mysql.connector import Error

try:
    # Connect to the MySQL server and database
    connection = mysql.connector.connect(
        host="localhost",
        user="your_username",
        password="your_password",
        database="your_database"
    )

    if connection.is_connected():
        print("Connected to MySQL database")

    # Create a cursor object
    cursor = connection.cursor()

    # Execute a DELETE query
    delete_query = "DELETE FROM employees WHERE id = %s"
    data = (1,)
    cursor.execute(delete_query, data)

    # Commit the transaction
    connection.commit()
    print("Record deleted successfully")

except Error as e:
    print(f"Error: {e}")

finally:
    if connection.is_connected():
        cursor.close()
        connection.close()
        print("MySQL connection is closed")

Complete Example

Here is a complete example that includes connecting to the MySQL server, executing a DELETE query, and handling exceptions.

import mysql.connector
from mysql.connector import Error

# Database connection details
host = "localhost"
user = "your_username"
password = "your_password"
database = "your_database"

try:
    # Connect to the MySQL server and database
    connection = mysql.connector.connect(
        host=host,
        user=user,
        password=password,
        database=database
    )

    if connection.is_connected():
        print("Connected to MySQL database")

    # Create a cursor object
    cursor = connection.cursor()

    # Execute a DELETE query
    delete_query = "DELETE FROM employees WHERE id = %s"
    data = (1,)
    cursor.execute(delete_query, data)

    # Commit the transaction
    connection.commit()
    print("Record deleted successfully")

except Error as e:
    print(f"Error: {e}")

finally:
    if connection.is_connected():
        cursor.close()
        connection.close()
        print("MySQL connection is closed")

Conclusion

Deleting data from a MySQL table using Python is straightforward with the mysql-connector-python library. By following the steps outlined above, you can easily connect to a MySQL database, execute delete queries, and handle exceptions effectively. This provides a solid foundation for managing and manipulating your data programmatically using Python.