-----------------------------------------------------------
5. Polygamisti
-----------------------------------------------------------
WITH muzi(idpolyg) AS (
  SELECT DISTINCT m1.id_manzel
  FROM rn_manzelstvo m1, rn_manzelstvo m2
  WHERE m1.id_manzel=m2.id_manzel   
    AND 
    (
      (m1.datum_od BETWEEN m2.datum_od AND m2.datum_do)
      OR 
      (m2.datum_od BETWEEN m1.datum_od AND m1.datum_do)
      OR
      (m1.datum_od > m2.datum_od AND m2.datum_do IS NULL)
      OR
      (m2.datum_od > m1.datum_od AND m1.datum_do IS NULL)
    )
   AND m1.id_manzelka<>m2.id_manzelka
)
SELECT c.meno, c.priezvisko
FROM muzi
JOIN rn_clovek c ON c.id=idpolyg