What are common pitfalls to avoid when integrating a PHP script with a webpage?

One common pitfall to avoid when integrating a PHP script with a webpage is not properly sanitizing user input, which can leave your website vulnerable to security risks such as SQL injection attacks. To solve this issue, always use prepared statements or parameterized queries when interacting with a database to prevent malicious code from being executed.

// Example of using prepared statements to prevent SQL injection
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = :username");
$stmt->bindParam(':username', $username);
$stmt->execute();