รบกวนช่วยชี้แนะ พวก session ทีค่ะ ทำมาแล้วมันเออเร่ออ่ะค่ะ ทำไปทำมาเละค่ะ รบกวนทีนะค่ะ

<?
session_start();

$id_pro = $_GET[PID];

$_SESSION["sess_idproduct"];
$_SESSION["sess_name_prd"];
$_SESSION["sess_price"];
$_SESSION["sess_num"];
$today = date("d-m-Y");  

	include("config.php");
	$sql="select * from products where id='$id_pro' ";
	//echo $sql;
	$result=mysql_query($sql);
	$rs=mysql_fetch_array($result);
	
if(count($sess_idproduct) == 0){
	 $_SESSION["sess_idproduct"]=$rs[productscode];
	 $_SESSION["sess_name_prd"]=$rs[productsname];
	$_SESSION["sess_price"]=$rs[productsprice];
	 $_SESSION["sess_num"]=1;
	
}else{
	$key = array_search($rs[productscode], $_SESSION["sess_idproduct"]);
	if(strlen($key) > 0){
		$sess_num[$key] = $sess_num[$key]+1;
	}else{
		$sess_idproduct[]=$rs[productscode];
		$sess_name_prd[]=$rs[productsname];
		$sess_price[]=$rs[productsprice];
		$sess_num[]=1;
	}
}

header("Location: cart_index.php");
?>

<?
session_start();
if (count($_SESSION["sess_idproduct"])==0) {
		
			echo "<br><br><center><font size=2 >.....ยังไม่สินค้าอยู่ในตะกร้าสินค้าของท่าน....<br></font></center><BR>";
	}
<?
					 // echo $_SESSION["sess_idproduct"];
				for ($i=0;$i<count( $_SESSION["sess_idproduct"]);$i++) {
					$total_unit = $_SESSION["sess_num"][$i]*$_SESSION["sess_price"][$i];
					$sum = $_SESSION["sess_num"][$i]*$_SESSION["sess_price"][$i];
					$total=$total+$total_unit;
					//$a = $sess_num[$i] *150 ;
					$a = $_SESSION["sess_num"][$i];
					$c=number_format($total_unit,2,'.',',') ;
					//$total_all=$total+$a;
					$total_all=$total;
					echo '
				          <TR bgcolor="#FFFFFF">
								
								<TD> <font size="2" color="#ff0000">'.$_SESSION["sess_name_prd"][$i].'</font> </TD>
								
								<TD><CENTER>
									<INPUT TYPE="text" NAME="prd_num[]" VALUE="'.$_SESSION["sess_num"][$i].'" SIZE="5" maxlength="5" onkeypress="return bannedKey(event)">
								</CENTER></TD>
								<TD><CENTER><font size="2" color="#003366">'.$_SESSION["sess_price"][$i].'</font></CENTER></TD>
								
								<TD><div align="right"><font size="2" color="#003366">'.$c.'</font></div></TD>
								<TD><CENTER>
									<INPUT TYPE="checkbox" NAME="prd_del[]" VALUE="'.$_SESSION["sess_idproduct"][$i].'">
								</CENTER></TD>

						 </TR>';
				}
			?>