I am making this for adding storage in an admin section of my site. I have encountered a very strange problem. $voorraad always equals 7, no matter what product I choose(id changes), it keeps coming up as 7. 

I am echoing $voorraad by making a session and echoing it in an other page.
The table name and column is correct. Can someone explain why $voorraad always equals seven?
If you need more code, I will provide it. 

```
 $cartItems = $cart->contents();
        foreach($cartItems as $item){
            $sql = ("SELECT voorraad FROM Producten WHERE id =".$item['id']);
            $voorraad = (float)mysql_query($sql);
            $itm = (float)$item['qty'];
            $_SESSION['voorraad'] = $voorraad;
            $_SESSION['itm'] = $itm;               
            $up = $itm + $voorraad;
            $sql1 = "UPDATE Producten SET voorraad = $up WHERE id =".$item['id'];
            $res = mysql_query($sql1);

        }

```