Please help with this query! Need to get taxonomy terms of related nodes
You already have the {term_node} table joined in your query so I'm pretty sure you should just be able to change your first line to include tn2.tid. Try this:

SELECT DISTINCT n.title, nr.teaser, n.nid, tn2.tid, DATE_FORMAT(FROM_UNIXTIME(n.created), '%M %e, %Y') AS date, f.filepath AS image, cfri.field_related_images_nid as image_id 
FROM node n JOIN node_revisions nr ON n.nid = nr.nid 
LEFT JOIN content_field_related_images cfri ON (n.nid = cfri.nid AND cfri.delta = 0) 
LEFT JOIN content_field_att_file cfaf ON cfri.field_related_images_nid = cfaf.nid 
LEFT JOIN files f ON cfaf.field_att_file_fid = f.fid  
JOIN term_node tn2 ON n.nid = tn2.nid 

WHERE n.status = 1 AND n.type = 'article'   AND nr.body LIKE '%kimberly-clark%' AND     tn2.tid = 143 ORDER BY n.created DESC LIMIT 3