ENTREGAS EN POST QUE NO ESTAN EN HOMEWORKS

SELECT * FROM 
cl_post_attachments p
LEFT JOIN cl_courses_homeworks_attachments h
ON 
p.attachment_to = h.attachment_to AND
p.attachment_target = h.attachment_target AND 
p.attachment_target_item = h.attachment_target_item AND
p.attachment_from = h.attachment_from AND
p.attachment_author = h.attachment_author

WHERE h.attachment_id IS NULL
AND p.attachment_to = 15;

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