Phantom spaces in listings

This behaviour is caused by \lstset{columns=fixed}. Changing to columns=flexible or columns=fullflexible should make it go away.

You could always provide the SQL code as "attachments" to the PDF. Of course, that might really only work with Acrobat Reader...

I could fix this problem by setting a different monospace font:

\newfontfamily\listingsfont[Scale=.7]{DejaVu Sans Mono}
\lstset{basicstyle=\listingsfont}

(This is more or less what @Jan Hlavacek describes in his comment)