SELECT
	*
FROM
	tbladressen
		LEFT JOIN
	(SELECT KmAdressNr FROM tblkdmerkmale WHERE KmBez = 'Privatkunde' GROUP BY _
  KmAdressNr) AS pQ1
		ON (AdressNr = pQ1.KmAdressNr)
		LEFT JOIN
	(SELECT KmAdressNr FROM tblkdmerkmale WHERE KmBez = '2011' OR KmBez = '2012' _
  GROUP BY KmAdressNr) AS pq2
		ON (AdressNr = pQ2.KmAdressNr)
WHERE
	pQ1.KmAdressNr IS NOT NULL
		AND
	pQ2.KmAdressNr IS NOT NULL