PHP 更新购物车数量

<form action="?action=edit_num" method="post" name="car<?php $c_rs['id'];?>" id="car<?php $c_rs['id'];?>">
<input name="suliang[<?php echo $c_rs['sp_id'];?>]" type="text" id="suliang[<?php echo $c_rs['sp_id'];?>]" value="<?php echo $c_rs['suliang'];?>"/>
<input type="submit" name="button" id="button" value="更新购物车"  />
</form>

<?php
require 'config.inc.php';
require 'checklogin.php';
$username = $_SESSION['username'];

$action = $_GET['action'];
switch ($action) {
case "edit_num":

$arr = $arr = $_POST['suliang'];
foreach($arr as $key=>$value){
$sqlgx = "update `cartemp` set suliang='$value' where username='".$username."' and flag=0 and sp_id='".$key."'";
mysql_query($sqlgx, $conn);
echo "<script>location.href='shopcat.php'</script>";
}
break;

case "null":
$null_sql = "delete from `cartemp` where username='$username' and flag=0 ";
mysql_query($null_sql, $conn);
echo "<script>location.href='shopcat.php'</script>";
break;

case "del":
$id = $_GET['id'];
$del_sql = "delete from `cartemp` where id=$id";
mysql_query($del_sql, $conn);
echo "<script>location.href='shopcat.php'</script>";
break;
}
?>