Hmmm. I think you may have the left join backwards. As written it is taking the cartesian product of Insula and Regio and then joining it to Image whenever there happens to be an image record that has that particular combination of Insula and Regio.

The table after the words "LEFT JOIN" is the table from which you want to select all records even if they have a NULL value in one or more foreign key fields. If you want to take each Image record and join it to Regio and Insula wherever possible, then you need to swap the first two LEFT JOINs, like this:

my $sth = $dbh->prepare( "SELECT * FROM Images 
  LEFT JOIN Images ON Images.RegioID = Regio.RegioID
  LEFT JOIN Images ON Images.InsulaID = Insula.InsulaID
  LEFT JOIN ImgThemes ON Images.ImageID = ImgThemes.ImageID
  LEFT JOIN Sources ON Images.SourceID = Sources.SourceID
  ORDER BY ImageName LIMIT $start,$numrows" );
[download]

Best, beth