Prueba esto
$catid = $_REQUEST['catid'];
$userid = $_REQUEST['userid'];
$sql= "SELECT p.catid, p.catname, p.productid, p.prodimg,
GROUP_CONCAT(p.prodsize ORDER BY p.id ASC) as size,
GROUP_CONCAT(p.cost ORDER BY p.id ASC) as cost, p.prodname,
GROUP_CONCAT(c.prodsize,'-',c.quantity) as cart_details, GROUP_CONCAT(DISTINCT(c.userid)) as user_id
FROM products p
LEFT JOIN cart c ON(c.productid = p.productid AND c.userid = '$userid' AND p.prodsize = c.prodsize)
WHERE p.catid ='$catid'
GROUP BY p.productid
ORDER BY user_id DESC, p.productid ASC";
$result = mysql_query($sql);
if (mysql_num_rows($result) > 0)
{
$i = 0;
while($row = mysql_fetch_assoc($result))
{
$rows[$i]['catid'] = $row['catid'];
$rows[$i]['catname'] = $row['catname'];
$rows[$i]['productid'] = $row['productid'];
$rows[$i]['prodname'] = $row['prodname'];
$rows[$i]['prodimg'] = $row['prodimg'];
$final_size = array_fill(0, 4, '0');
$final_cost = array_fill(0, 4, '0');
$size = explode(',', $row['size']);
$cost = explode(',', $row['cost']);
foreach($size as $k=>$sizecol) {
switch($sizecol) {
case 'small':
$array_key = '0';
break;
case 'medium':
$array_key = '1';
break;
case 'large':
$array_key = '2';
break;
case 'perpiece':
$array_key = '3';
break;
}
$final_size[$array_key] = $sizecol;
$final_cost[$array_key] = $cost[$k];
}
$cart_details = explode(',', $row['cart_details']);
$purchasedsize = array_fill(0, 4, '0'); //Since you displayed this array has 4 values only
$purchasedquantity = array_fill(0, 4, '0');
foreach($cart_details as $cart) {
if($cart != '') {
$details = explode('-', $cart);
$key = array_search($details[0], $size);
$purchasedsize[$key] = $details[0];
$purchasedquantity[$key] = $details[1];
}
}
$rows[$i]['size'] = $final_size;
$rows[$i]['cost'] = $final_cost;
$rows[$i]['purchasedsize'] = $purchasedsize;
$rows[$i]['purchasedquantity'] = $purchasedquantity;
$rows[$i]['userid'] = $row['user_id'];
$i++;
}
}
echo "<pre>";
print_r($rows);
echo "</pre>";
La matriz de salida
Array
(
[0] => Array
(
[catid] => 2
[catname] => c1
[productid] => 13
[prodname] => P1
[prodimg] =>
[size] => Array
(
[0] => small
[1] => medium
[2] => large
[3] => perpiece
)
[cost] => Array
(
[0] => 10
[1] => 20
[2] => 30
[3] => 12
)
[purchasedsize] => Array
(
[0] => small
[1] => 0
[2] => large
[3] => 0
)
[purchasedquantity] => Array
(
[0] => 2
[1] => 0
[2] => 1
[3] => 0
)
[userid] => 1
)
[1] => Array
(
[catid] => 2
[catname] => c1
[productid] => 14
[prodname] => P2
[prodimg] =>
[size] => Array
(
[0] => small
[1] => medium
[2] => large
[3] => 0
)
[cost] => Array
(
[0] => 15
[1] => 20
[2] => 25
[3] => 0
)
[purchasedsize] => Array
(
[0] => 0
[1] => medium
[2] => 0
[3] => 0
)
[purchasedquantity] => Array
(
[0] => 0
[1] => 1
[2] => 0
[3] => 0
)
[userid] => 1
)
[2] => Array
(
[catid] => 2
[catname] => C1
[productid] => 15
[prodname] => P3
[prodimg] =>
[size] => Array
(
[0] => 0
[1] => medium
[2] => 0
[3] => perpiece
)
[cost] => Array
(
[0] => 0
[1] => 20
[2] => 0
[3] => 18
)
[purchasedsize] => Array
(
[0] => 0
[1] => 0
[2] => 0
[3] => 0
)
[purchasedquantity] => Array
(
[0] => 0
[1] => 0
[2] => 0
[3] => 0
)
[userid] =>
)
)
