SELECT uid, ean_einzelstueck, uid_product
FROM tx_commerce_articles
WHERE ean_einzelstueck IN (
SELECT ean_einzelstueck
FROM tx_commerce_articles
WHERE ean_einzelstueck != ''
AND deleted = 0
AND hidden = 0
AND l18n_parent = 0
GROUP BY ean_einzelstueck
HAVING count(ean_einzelstueck) < 1
)
ORDER BY ean_einzelstueck, uid;