How can PHP developers ensure the secure deployment of their scripts, especially when testing in internal networks before going live?

PHP developers can ensure the secure deployment of their scripts by following best practices such as using parameterized queries to prevent SQL injection, validating and sanitizing user input, implementing proper authentication and authorization mechanisms, and keeping sensitive information secure by not hardcoding passwords or API keys in the code. When testing in internal networks before going live, developers should ensure that the network is secure and access is restricted to authorized personnel only.

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