Try
Code:
select Title from CONTENT
where BookID is null and ContentType=6 and Accessibility <> 6 and Accessibility <> 4
order by title;
I'm not certain about Accessibility but a quick perusal seemed to show those were books I did not actually have, possibly previews
EDIT: From browsing DavidFor's calibre driver it looks like 4 is Recommendations and 6 Previews.