Check quantity of an item

[Abronsyth]

OK I know I did something terribly unintelligent to get this error;
Fatal error: Uncaught exception 'Exception' with message 'Sorry, you only have Rock Cone, you need 10!' in /home/arieng/catisserie.net/view/completeq1view.php:48 Stack trace: #0 /home/arieng/catisserie.net/view/completeq1view.php(13): Completeq1View->takeItem('Rock Cone', 10) #1 /home/arieng/catisserie.net/classes/class_frontcontroller.php(100): Completeq1View->index() #2 /home/arieng/catisserie.net/index.php(74): FrontController->render() #3 /home/arieng/catisserie.net/index.php(78): IndexController::main() #4 {main} thrown in /home/arieng/catisserie.net/view/completeq1view.php on line 48

I'm sure this will make you cringe to look at but this is the file thus far;

PHP Code:

<?php 

class Completeq1View extends View{ 
     
    public function index(){ 
        $mysidia = Registry::get("mysidia"); 
        $document = $this->document; 
        $document->setTitle("Turn in 10 Rock Cones");

            // Allow user to complete quest if they have not yet.  
            if ($mysidia->user->quest1 = "no") {                  
                        $document->add(new Comment("<center>Text Text Text<center>", FALSE));
                    $this->takeItem("Rock Cone",10);
                    }        
            else{
                $document->add(new Comment("The man furrows his brows at you, <b>sorry, no reward if you don't have any rock cones.</b>", FALSE));
                }
    }

public function takeItem($item, $qty){
    $mysidia = Registry::get("mysidia");
    $owned = $mysidia->db->select("inventory", array("quantity"), "itemname ='{$item}' and owner ='{$mysidia->user->username}'")->fetchColumn();
    if ($owned >= $qty){ 
        // If the user owns $qty amount or more...
        if ($owned == $qty){ 
            $amount = 100;
            $mysidia->user->changecash($amount);                    
                $document->add(new Comment("<center>You return to the scientit's camp and present the head scientist with 10 rock cones.<br>
                <b>Wow, thank you! Here are some kibs!</b><br>
                You've obtained {$amount} kibs!</center>", FALSE));
                // Update that they have done the quest 
                $mysidia->db->update("users", array("quest1" => "yes"), "username = '{$mysidia->user->username}'");
            // If the user has exactly $qty left, delete the whole row.
             $mysidia->db->delete("inventory", "itemname='{$item}' and owner='{$mysidia->user->username}'");
            $amount = 100;
            $mysidia->user->changecash($amount);                    
                $document->add(new Comment("<center>You return to the scientit's camp and present the head scientist with 10 rock cones.<br>
                <b>Wow, thank you! Here are some kibs!</b><br>
                You've obtained {$amount} kibs!</center>", FALSE));
                // Update that they have done the quest 
                $mysidia->db->update("users", array("quest1" => "yes"), "username = '{$mysidia->user->username}'");
         } else {
            // Subtract $qty from user's inventory.
            $owned_left = $owned - $qty;
            $mysidia->db->update("inventory", array("quantity" => $owned_left), "itemname ='{$item}' and owner='{$mysidia->user->username}'");  
        }
    } else {
        throw new Exception("Sorry, you only have {$owned} {$item}, you need {$qty}!"); 
    }
}    

    
}
?>

Edit;
OK, may be because I didn't actually define $qty at any point...not really sure how to, though @_@ I know that you can see if a user owns a certain item, but not sure how to define $qty to check how many of that item they own.