10 Common PHP Mistakes Beginners Make (and How to Avoid Them)

Introduction

Learning PHP is exciting, but it’s easy to fall into bad habits that can cause bugs, security issues, or performance problems. In this post, we’ll go over 10 common mistakes PHP beginners make—and how you can avoid them.

1. Not Using Error Reporting

By default, PHP may hide errors. Beginners often miss important warnings and notices.

Solution: Enable error reporting in your development environment:

ini_set("display_errors", 1);
error_reporting(E_ALL);

2. Mixing HTML and PHP Without Structure

Throwing PHP directly into HTML without a plan leads to messy, hard-to-maintain code.

Solution: Separate logic from presentation using templates or frameworks like Laravel.

3. Ignoring Prepared Statements

Using raw SQL with variables can make your app vulnerable to SQL injection.

Solution: Use prepared statements with PDO or MySQLi:

$stmt = $pdo->prepare("SELECT * FROM users WHERE email = ?");
$stmt->execute([$email]);

4. Using $_GET and $_POST Without Validation

Directly using user input can lead to security issues.

Solution: Always validate and sanitize input using filter_input() or custom functions.

5. Forgetting to Escape Output

Not escaping data before displaying it can allow Cross-Site Scripting (XSS) attacks.

Solution: Use htmlspecialchars() when outputting data:

echo htmlspecialchars($userInput, ENT_QUOTES, "UTF-8");

6. Hardcoding Configuration Values

Putting database credentials or API keys directly in code makes them hard to change and insecure.

Solution: Store configuration in environment variables or a config file outside the web root.

7. Not Using Strict Comparisons

Using == can cause unexpected type juggling.

Solution: Use === for strict comparisons.

8. Not Using Version Control

Beginners sometimes skip Git, making it hard to track changes or collaborate.

Solution: Learn basic Git commands and use it for all projects.

9. Poor Error Handling

Relying on die() or ignoring errors entirely can break your app unexpectedly.

Solution: Use try...catch blocks and meaningful error messages.

10. Not Keeping PHP Updated

Using outdated PHP versions can cause security vulnerabilities and compatibility issues.

Solution: Always run the latest stable PHP version supported by your framework or CMS.

Conclusion

Avoiding these common mistakes will make your PHP code more secure, maintainable, and professional. Start applying these best practices today, and you’ll see immediate improvements in your development skills.