Prevent SQL Injection in PHP: 6 Simple Tips for Secure Code

To prevent SQL injection in PHP, you should use prepared statements with parameterized queries. Here’s how you can do it:

1. Prepared Statements: Use prepared statements with placeholders for variables in your SQL queries. Prepared statements act as a sturdy barrier, cordoning off SQL logic from data, thus thwarting any attempts by attackers to infiltrate with malicious SQL code.
   
   Example using PDO (PHP Data Objects):
   $stmt = $pdo->prepare("SELECT * FROM users WHERE username = ?");
$stmt->execute([$username]);
$user = $stmt->fetch();
   
   Example using MySQLi (MySQL Improved):
   $stmt = $mysqli->prepare("SELECT * FROM users WHERE username = ?");
$stmt->bind_param("s", $username);
$stmt->execute();
$result = $stmt->get_result();
$user = $result->fetch_assoc();
2. Input Sanitization: Sanitize user input to remove any potentially harmful characters before using them in SQL queries. However, this should not be solely relied upon for preventing SQL injection. It’s recommended to use prepared statements instead.
3. Use ORM Libraries: Consider using Object-Relational Mapping (ORM) libraries like Doctrine or Eloquent, which handle database interactions safely and abstract away SQL queries.
4. Database User Permissions: Limit the permissions of the database user used by your application to only those necessary for its operation. Steer clear of utilizing privileged accounts for your database connections, as it fortifies your defense against potential breaches and unauthorized access attempts.
5. Regular Updates: Keep your PHP version and database software up to date to ensure you have the latest security patches and features.
6. Error Handling: Implement proper error handling to handle database errors gracefully without exposing sensitive information to users.

By following these practices, you can significantly reduce the risk of SQL injection vulnerabilities in your PHP applications.