$host = '127.0.0.1';
	$db   = 'myguests';
	$user = 'root';
	$pass = '12345';
	$charset = 'utf8';

	$dsn = "mysql:host=$host;dbname=$db;charset=$charset";
	$opt = [
	    PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
	    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
	    PDO::ATTR_EMULATE_PREPARES   => false,
	];
	$pdo = new PDO($dsn, $user, $pass, $opt);

	try {
    $pdo->prepare("INSERT INTO MyGuests (firstname, lastname, email) VALUES ($firstName, $lastName, $email)")->execute($data);
	} catch (PDOException $e) {
	    if ($e->getCode() == 1062) {
	        // Take some action if there is a key constraint violation, i.e. duplicate name
	    } else {
	        throw $e;
	    }
	}