PHP url shortener

<?php
$servername = "localhost";
$username = "niets";
$password = "ook niets";
$dbname = "nogeens niets";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$stmt = $dbh->prepare("INSERT INTO URLshort (ID, URL) VALUES (:ID, :URL)");
$stmt->bindParam(':ID', $ID);
$stmt->bindParam(':URL', $URL);

// insert one row
$ID = 'rickroll';
$URL = 'neva gonna give u up';
$stmt->execute();


$conn->close();
?>