verify email script - suggestions?

Code:

$data = array('user_code' => "activated");

    $where = "user_code = ".$this->uri->segment(3);

    $query = $this->db->update('users', $data, $where); 



    return $query;

Code:

$rand_code = random_string('alnum', 10);

$this->Profile_model->save('Add',$rand_code,'');



//Sending mail and link part :



$to = $this->input->post('email');

                $fromemail = $this->config->item('admin_email');

                $fromname = site_name();

                //$this->email->from($this->config->item('admin_email'), site_name());

                $message = "Hello $name, \n\nThank you for registering with BrightPocket.\n\n\nUsername : $username \n\nPassword : $password \n\n\nPlease click on the link in order to activate your account\n\n";

                  $message .= site_url()."/profile/activate/".$rand_code;

                $subject = "Complete Registration";

                mail($to, $subject, $message, "From: $fromname<$fromemail>" );



function activate($code)

     {

           $code = $this->db->escape_str($code);

           $sql = "SELECT id FROM members WHERE activation_code = '".$code."' LIMIT 1";

           $query = $this->db->query($sql);

           if($query->num_rows() == 1)

           {

                 $sql = "UPDATE members SET active = 1 WHERE activation_code = '".$code."' AND active = 0";

                 $this->db->query($sql);

                 $this->data['alert'] = 'Your account has been successfully verified. Login to access your account';

                 $this->load->view('profile/signin', $this->data);

                 return TRUE;

           }

           return FALSE;

     }