Python MySQL: How to Use the LIMIT Clause

In database operations, retrieving a specific number of rows can be crucial for performance and clarity. The LIMIT clause in MySQL allows you to control the number of rows returned by a query. This tutorial will show you how to use the LIMIT clause in Python with MySQL.

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Prerequisites

Before starting, ensure you have the following:

  • Python Installed: Download from python.org.
  • MySQL Server Installed: Install via MySQL official site.
  • MySQL Connector for Python: Install with pip: 
pip install mysql-connector-python

What is the LIMIT Clause?

The LIMIT clause is used to specify the maximum number of rows returned by a query. It is especially useful when working with large datasets or when you want to paginate results in your application.

How to Use LIMIT in Python with MySQL

Step 1: Connect to the Database

First, connect to your MySQL database:

import mysql.connector

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

print("Connected to the database!")

Replace your_username, your_password, and your_database with your MySQL credentials.

Step 2: Fetch a Limited Number of Rows

To limit the number of rows returned, use the LIMIT keyword:

cursor = db.cursor()

sql = "SELECT * FROM users LIMIT 5"  # Replace 'users' with your table name
cursor.execute(sql)

result = cursor.fetchall()

for row in result:
    print(row)

The above query retrieves only the first 5 rows from the users table.

Step 3: Use LIMIT with OFFSET

To fetch rows starting from a specific position, use LIMIT with OFFSET. This is useful for implementing pagination:

sql = "SELECT * FROM users LIMIT 5 OFFSET 10"  # Skips the first 10 rows and fetches the next 5
cursor.execute(sql)

result = cursor.fetchall()

for row in result:
    print(row)

Step 4: Dynamic LIMIT and OFFSET

For more flexibility, pass the limit and offset values as parameters:

sql = "SELECT * FROM users LIMIT %s OFFSET %s"
val = (5, 10)  # Fetch 5 rows, skipping the first 10
cursor.execute(sql, val)

result = cursor.fetchall()

for row in result:
    print(row)

This method is safer and helps prevent SQL injection.

Full Python Code Example

Here’s a complete example of using the LIMIT clause with Python and MySQL:

import mysql.connector

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

cursor = db.cursor()

# Fetch a limited number of rows with offset
limit = 5
offset = 10

sql = "SELECT * FROM users LIMIT %s OFFSET %s"
val = (limit, offset)
cursor.execute(sql, val)

result = cursor.fetchall()

for row in result:
    print(row)

# Close the connection
db.close()

Exercises

Exercise 1: Fetch the Top 10 Records

Write a script to fetch the first 10 rows from the orders table.

Exercise 2: Paginate Results

Create a script that fetches and displays rows in pages of 5 from the products table.

Exercise 3: Dynamic Pagination

Build a program that takes user input for page number and displays rows accordingly.

Why Use the LIMIT Clause?

  • Performance Optimization: Fetching fewer rows reduces database load.
  • Pagination: Enables smooth navigation in web and mobile applications.
  • Data Management: Focuses on the most relevant data for analysis or display.

Conclusion

The LIMIT clause is a powerful tool for managing large datasets and ensuring optimal performance in database queries. Using Python, you can integrate it seamlessly into your applications for tasks like pagination and selective data retrieval.

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