Session Problem in Shopping Cart

nitediver

This is simple shopping cart, it's using session to carry data.
It using three different page:
1.php : Display the product & size(option list)
2.php : Use for passing data to 3.php
3.php : Display the data, iterate value using foreach().

1.php

<?
include "function.php";
connect();
session_start();

$qprod = mysql_fetch_array(mysql_query("SELECT * FROM a_prod WHERE prod_id='11'"));
$qsize = mysql_query("SELECT * FROM a_size ORDER BY size_id ASC");

echo ("
<form name=\"update\" method=\"post\" action=\"2.php?prod_id=$qprod[prod_id]&size_id=$size_id&action=add\">
Size <select name=\"size_id\">
");

while($rsize=mysql_fetch_array($qsize))
{echo ("<option value=$rsize[size_id]> $rsize[size_number] </option>");}
echo ("
</select>
<input type=\"submit\" value=\"Submit\" name=\"submit\">
</form>
");
?>

2.php

<?
include "function.php";
connect();
session_start();

$action = $_GET['action'];
$prod_id = $_SESSION['prod_id'] = $_GET['prod_id'];
$prod_id = $_SESSION['size_id'] = $_GET['size_id'];

$size_id = $_SESSION['size_id'] = htmlentities($_POST['size_id'], ENT_QUOTES);

switch($action){
	case "add":
	$_SESSION['cart'][$prod_id]++;
	$_SESSION['cart'][$size_id]++;
	break;
	case "remove":
	$_SESSION['cart'][$prod_id]--;
	$_SESSION['cart'][$size_id]--;
	break;
	case "empty":
	session_destroy();
	break;
}
header("location:3.php");
?>

3.php

<?
include "function.php";
connect();
session_start();

$prod_id = $_SESSION['prod_id'];
//$size_id = $_SESSION['size_id'];

$c = count($_SESSION['cart']);
echo "Session Amount : ".$c."<br>";

if(!$_SESSION['cart'])
{
	echo "Cart Empty!";
}else{
	foreach($_SESSION['cart'] as $size_id => $q)
	{
	$prod = mysql_query("SELECT size_id,size_number,prod_name FROM a_size,a_prod WHERE size_id='$size_id' AND prod_id='$prod_id'");

	if(mysql_num_rows($prod) > 0)
	{
	list($size_id, $size_number, $prod_name) = mysql_fetch_row($prod);
		if($q > 0)
		{
		echo "Name : ".$prod_name." - "."Size : ".$size_number." - "."Qty : ".$q.
		"<a href=\"2.php?prod_id=$prod_id&size_id=$size_id&action=remove\"> - </a><br>";
		}
	}
}

}
?>

The result on 3.php shown like this:
Session Amount : 4
Name : Fade It - Size : 40 - Qty : 3 -
Name : Fade It - Size : 42 - Qty : 2 -
Name : Fade It - Size : 41 - Qty : 1 -

But when I change the product id in 1.php & submit them, all of the product name change:
Session Amount : 4
Name : Sonar - Size : 40 - Qty : 3 -
Name : Sonar - Size : 42 - Qty : 3 -
Name : Sonar - Size : 41 - Qty : 1 -

That is my problem, I want to carry more than one value(prod_id & size_id), so the result I am expecting is like this:
Name : Fade It - Size : 40 - Qty : 2 -
Name : Berra - Size : 42 - Qty : 3 -
Name : Sonar - Size : 41 - Qty : 1 -

Some other things make me curious is these part, in 2.php:

$prod_id = $_SESSION['prod_id'] = $_GET['prod_id'];
$prod_id = $_SESSION['size_id'] = $_GET['size_id'];

If I set the second line into $size_id, it display blank page on 3.php.

Hope anyone will help me, working with foreach loops is quite complicated for me.
Sorry for long code & explanation, thanks.

nitediver

This is table of product & size, hope it help to answer my question.

Product

[CODE]

prod_id | prod_name | prod_price

7 | Fade | 39

8 | Sonar | 49

[/CODE]

Size

[CODE]

size_id | size_number

1 | 40

2 | 41

3 | 42

[/CODE]

nitediver

I have made few changes, but something weird happen, for the first submission it appear to be normal. On the second submission and so on(with same product & size), the size_id is increment [1]40 > [2]41 > [3]42:
1.First submission : Fade 40 >> Name : Fade - Size : 40 - Qty : 1 -
2.Second submission: Fade 40 >> Name : Fade - Size : 41 - Qty : 2 -

Since I only have 3 size in my table, when the product submit four times it display nothing.

It also happen for same product but different size, keep getting the first size in table rather chosen one.

It display these:
Name : Sonar - Size : 40 - Qty : 1 -
Name : Sonar - Size : 40 - Qty : 1 -

Rather than this:
Name : Sonar - Size : 40 - Qty : 1 -
Name : Sonar - Size : 42 - Qty : 1 -

I try to put if around the case "add" on 2.php, with condition "if the size exist it will only increment the product", but it did not work.

3.php

<?
	foreach($_SESSION['cart'] as $item=>$sizes)
	{
		foreach($sizes as $size)
		{
		$prod = mysql_query("SELECT prod_name,size_id,size_number FROM a_prod,a_size WHERE prod_id='$item' AND size_id='$size'");

		if(mysql_num_rows($prod) > 0)
		{
		list($prod_name, $size_id, $size_number) = mysql_fetch_row($prod);

			echo "Name : ".$prod_name." - "."Size : ".$size_number." - "."Qty : ".$size.
			"<a href=\"2.php?prod_id=$prod_id&size_id=$size_id&action=remove\"> - </a><br>";

		}
	}
}
}
?>

dagon

you need to narrow it down to the simplest example of the issue, no one is going to read through all that.