เปลี่ยนค่า textbox session จำนวน ใน form cart ไม่ได้

   <?
	  
	
	foreach($_SESSION["ses_p_nameid"] as $key=>$value){

?>
        <tr>
          <td align="center" bgcolor="#F0F0F0" class="font_menu"><?=$_SESSION['ses_p_nameid'][$key]?></td>
          <td align="center" bgcolor="#F0F0F0" class="font_menu"><?=$_SESSION['ses_pro_name'][$key]?></td>
          <td align="center" bgcolor="#F0F0F0" class="font_menu"><?=$_SESSION['ses_pro_price'][$key]?></td>
          <td align="center" bgcolor="#F0F0F0" class="font_menu"><?=$_SESSION['ses_pro_send'][$key]?></td>
          <td align="center" bgcolor="#F0F0F0" class="font_menu"><p>
            
         
            <input  type="text" name="qa" id="qa" value="<?=$_SESSION['ses_pro_qty'][$key]?>" size="1" maxlength="3" />
            </a></p></td>
          <td align="center" bgcolor="#F0F0F0" class="font_menu"><?=$_SESSION['ses_p_sum'][$key] = (($_SESSION['ses_pro_price'][$key] + $_SESSION['ses_pro_send'][$key]) * $qa);?></td>
          <td align="center" bgcolor="#F0F0F0" class="font_menu"><p><a href="javascript:if(confirm('ลบรายการสินค้า')==true){window.location='?do=cart&amp;did=<?=$_SESSION['ses_p_nameid'][$key]?>';}"><img src="images/del.jpg" width="32" height="32" border="0" /></a></p></td>
        </tr>
        <?
		$i++;
  }
?>

<?php header ('Content-type: text/html; charset=utf-8');

session_start();
//session_destroy();
	//  Cart
	if (!isset($_SESSION["cart"])) {
		$_SESSION["cart"] = array();
	}
	
	$data = array(
							array("id"=>1, "name"=>"โอวันติล", "price"=>"250", "amount"=>"1"),
							array("id"=>2, "name"=>"ไมโล", "price"=>"399", "amount"=>"2"),
							array("id"=>3, "name"=>"ชาเขียว", "price"=>"89", "amount"=>"3")
							);

	$c = count($data);

	for ($rs = 0; $rs < $c; $rs++)
	{
		$_SESSION["cart"][$data[$rs]["id"]] = array("name" => $data[$rs]["name"], "price" => $data[$rs]["price"], "amount" =>$data[$rs]["amount"]);
	}

	// ลบออกตาม removeID=x
	// เรียกใช้แบบนี้ครับ   http://localhost/testzone/cart.php?removeID=1  2  3  อะไรก็ว่าไปตาม id ของ array
	unset($cart[$_GET['removeID']]);
	
	
	// update  เรียกใช้แบบนี้ครับ   http://localhost/testzone/cart.php?update=update
	// สังเกตจำนวนจะเปลี่ยนไปนะ
	if($_GET['update']=="update"){
		$data_new = array(
								array("id"=>1, "name"=>"โอวันติล", "price"=>"250", "amount"=>"5"),
								//array("id"=>2, "name"=>"ไมโล", "price"=>"399", "amount"=>"6"),
								array("id"=>3, "name"=>"ชาเขียว", "price"=>"89", "amount"=>"7")
								);
		
		$c_new = count($data_new);
		for ($rs = 0; $rs < $c_new; $rs++)
		{
			$_SESSION["cart"][$data_new[$rs]["id"]] = array("name" => $data_new[$rs]["name"], "price" => $data_new[$rs]["price"], "amount" =>$data_new[$rs]["amount"]);
		}
	}


echo "<table border='1'>
	<tr>
		<td>ID</td>
		<td>Name</td>
		<td>Price</td>
		<td>Amount</td>
		<td>Total</td>
	</tr>
";


$cart = $_SESSION["cart"];

foreach($cart as $key=>$val){
	$total = $val['price'] * $val['amount'];
	$grandTotal = $grandTotal + $total;

	echo "
	<tr>		
		<td>".$key."</td>
		<td>".$val['name']."</td>
		<td>".$val['price']."</td>
		<td>".$val['amount']."</td>
		<td>".$total."</td>
	</tr>
	";
}
echo "<tr><td colspan='4' align='right'>ราคารวม</td><td>".$grandTotal."</td></tr>";
echo "</table> ";
?>