simple get like this

echo $this->input->get('my_id');
Load the URL helper To get current url

$currentURL = current_url(); //http://myhost/main

$params   = $_SERVER['QUERY_STRING']; //my_id=1,3

$fullURL = $currentURL . '?' . $params; 

echo $fullURL;   //http://myhost/main?my_id=1,3