Yii handles both query string variables and params nicely by putting them into $_GET. But it's sort of a pain to have to work with $_GET array. It would be helpful to have;
<?php
// class CWebApplication
public function getUrlParam($name, $default = null)
{
return (isset($_GET)? $_GET: $default);
}
?>
So you can do
<?php
$search = Yii::app()->getUrlParam('search', 'all');
// otherwise you are forced to ugly it up 
$search = (isset($_GET['search'])? $_GET['search']: 'all');
?>