php - How to update the quantity of all items in the cart with respect to database? -

i doing shopping cart using code-igniter. while can add cart functions, i'm confused how update them regards database. want when change item quantity in cart , click update ,both cart , database must updated particular item.i tried couldn't it.can please enlighten me do?

controller code

 $this->load->model('user_m');     $result['query'] = $this->user_m->get($id); // inserts coresponing item     foreach ($result['query'] $row)           $id = $row->pid;         $qty = $a;         $quan=$row->quantity;         $price = $row->pprice;     $name = $row->pname;      $q=$quan-$a;     // remainig stock i.e total qty-user qty         $data = array(         'id' => $id,         'qty' => $qty,         'price' => $price,         'name' => $name,         'stock' =>$q     );      $this->cart->insert($data);      $this->load->model('user_m');     $result['qry'] = $this->user_m->up_cart($id,$q);    redirect($_server['http_referer']);   } 

just tell me how update pls!

when ever add product in cart, generate uniq row id , unique each , every product , hence need update quantity row id

       $data = array(            'rowid' => 'b99ccdf16028f015540f341130b6d8ec',            'qty'   => 3         );        $this->cart->update($data); 

// or multi-dimensional array

       $data = array(            array(                    'rowid'   => 'b99ccdf16028f015540f341130b6d8ec',                    'qty'     => 3                 ),            array(                    'rowid'   => 'xw82g9q3r495893iajdh473990rikw23',                    'qty'     => 4                 ),            array(                    'rowid'   => 'fh4kdkkkaoe30njgoe92rkdkkobec333',                    'qty'     => 2                 )         );        $this->cart->update($data);  

now want know how row id.

      $cart=$this->cart->contents(); 

it return whole array of cart , when listing on webpage, please associate row id quantity text box update particular product.

please check following url:

https://ellislab.com/codeigniter/user-guide/libraries/cart.html