CREATE OR REPLACE PROCEDURE PERIODE_MINSTE_OPNAMES
IS
  TYPE type_coll_periodes IS TABLE OF periode%ROWTYPE;
  t_periodes type_coll_periodes;
  v_index PLS_INTEGER;
BEGIN
  SELECT pe.*
  BULK COLLECT INTO t_periodes
  FROM Periode pe
  WHERE pe.begindatum IN(SELECT pe1.begindatum
                         FROM Periode pe1, Opname op1
                         WHERE op1.datum BETWEEN pe1.begindatum AND pe1.einddatum
                         HAVING COUNT(op1.rolnr) =
                              (SELECT MIN(COUNT(op2.rolnr))
                               FROM Opname op2, Periode pe2
                               WHERE op2.datum BETWEEN pe2.begindatum AND pe2.einddatum
                               GROUP BY pe2.begindatum)
                         GROUP BY pe1.begindatum);

  v_index := t_periodes.FIRST;

  WHILE v_index IS NOT NULL
  LOOP
    DBMS_OUTPUT.PUT_LINE(t_periodes(v_index).begindatum || ' ' || t_periodes(v_index).einddatum || ' ' || t_periodes(v_index).plaatsnaam);

    v_index := t_periodes.next(v_index);
  END LOOP;
END PERIODE_MINSTE_OPNAMES;