CREATE TABLE personal (
     land text,
     stadt text,
     abteilung text,
     name text
 );

 INSERT INTO personal VALUES
     ('DE', 'Berlin', 'Vertrieb', 'Christian'),
     ('DE', 'Berlin', 'Marketing', 'Sandra'),
     ('DE', 'Frankfurt', 'Vertrieb', 'Stefan'),
     ('AT', 'Innsbruck', 'Personal', 'Katrin'),
     ('CH', 'Zürich', 'Vertrieb', 'Alexander');

 SELECT land, count(*) FROM personal GROUP BY land;
 SELECT land, stadt, count(*) FROM personal GROUP BY land, stadt;
 SELECT abteilung, count(*) FROM personal GROUP BY abteilung;
 SELECT land, abteilung, count(*) FROM personal GROUP BY land, abteilung;