tse mabut' faily "systemni", ne pryvyazani do kursiv. w SQL query treba zaminyty JOINy na LEFT JOIN'y, schos' jak v:
SELECT mdl_course.shortname, mdl_files.filename, mdl_files.filesize/1024.00 AS "size, KB"
FROM mdl_files
LEFT JOIN mdl_context ON (mdl_files.contextid = mdl_context.id)
LEFT JOIN mdl_course ON (mdl_course.id = mdl_context.instanceid)
WHERE mdl_files.filesize > 0
ORDER BY mdl_files.filesize;