try {
    $db = new PDO("mysql:host=localhost;dbname=gamesite",
            "root","root");
    if (isset ($_POST['newlogin'])){
           $newpassword = $_POST['newpassword'];
           $newusername = $_POST['newusername'];

    $query = $db->prepare("INSERT INTO users(username, password)
            VALUES(:username, :password )");
    $query->bindParam("username", $newusername);
    $query->bindParam("password", $newpassword);

    $checkquery = $db->prepare("SELECT username FROM users WHERE username='$newusername'");
    $checkquery->execute();
    $result = $checkquery -> fetchAll(PDO::FETCH_ASSOC);
    if($result->num_rows > 0){
    echo "Username already exists";
    }
   else{
       $query->execute();
        echo "Account created, you can login now";
    }
 }
} catch(PDOException $e) {
    die("Error: " . $e->getMessage());
}