How can PHP developers ensure efficient and secure handling of database queries and results when working with MySQL databases?

To ensure efficient and secure handling of database queries and results when working with MySQL databases in PHP, developers should use parameterized queries to prevent SQL injection attacks and properly handle errors to avoid exposing sensitive information. Additionally, developers should sanitize user input and validate data before executing queries.

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