How to select data from joined table

Move r.id from main query to condition

PHP Code:

if ($to == 'below')
{
    $query->select('r.id')
    -> // etc
} 


That's it. I had something like this in mind, but as the whole select. I didn't that because of a clean code (as good as I can *g). That I can add things to the select part is nice.

Thank you!