1) SELECT
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7) SELECT name FROM t_kunden WHERE kunden_nr IN (SELECT DISTINCT kunden_nr FROM t_bestellungen WHERE lieferdatum IS NULL)
8) SELECT t_kunden.kunden_nr, t_kunden.name, t_girokonten.blz, t_girokonten.kontonr FROM t_kunden LEFT JOIN t_girokonten ON (t_girokonten.kunden_nr = t_kunden.kunden_nr)
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10) SELECT b.kunden_nr FROM (SELECT kunden_nr, COUNT(*) AS anzahl FROM t_bestellungen GROUP BY kunden_nr) AS b WHERE b.anzahl IN (SELECT MAX(anzahl) FROM (SELECT kunden_nr, COUNT(*) AS anzahl FROM t_bestellungen GROUP BY kunden_nr))
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