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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" );

Best, beth


In reply to Re: DBI MySQL Join Question by ELISHEVA
in thread DBI MySQL Join Question by Jazz

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