foutje in sql syntax

$query = "UPDATE fuivenkalender SET check='1' WHERE id='".$_GET['id']."'";

$query = "UPDATE fuivenkalender SET check='1' WHERE id='".$_GET['id']."'";

<?php
$query = "UPDATE 
                  fuivenkalender
              SET 
                  check= 1 
              WHERE 
                   id= " .$_GET['id']. "
               ";
?>

<?php
$query = "UPDATE 
                  fuivenkalender
              SET 
                  check= 1 
              WHERE 
                   id= " .$_GET['id']. "
               ";
?>

<?php
$query = mysql_query("UPDATE 
                  fuivenkalender
              SET 
                  check= 1 
              WHERE 
                   id= " .$_GET['id']. "
               ") or die(mysql_error());
?>

<?php
$query = mysql_query("UPDATE 
                  fuivenkalender
              SET 
                  check= 1 
              WHERE 
                   id= " .$_GET['id']. "
               ") or die(mysql_error());
?>