CREATE OR REPLACE
PROCEDURE PERIODE_MINSTE_OPNAMES
IS

TYPE type_tab_datums IS TABLE OF opname.datum%TYPE
INDEX BY PLS_INTEGER;
t_datums type_tab_datums;

TYPE type_tab_periodes IS TABLE OF periode%ROWTYPE
INDEX BY PLS_INTEGER;
t_periodes type_tab_periodes;

t_periode_minste_opnames type_tab_periodes;

teller NUMBER;

BEGIN

  SELECT DISTINCT datum BULK COLLECT INTO t_datums
  FROM opname
  WHERE datum IS NOT NULL
  GROUP BY datum
  HAVING COUNT(datum) <= 1
  ORDER BY datum ASC;

  SELECT * BULK COLLECT INTO t_periodes
  FROM PERIODE;

  teller := 1;

  FOR i IN 1..t_datums.COUNT LOOP

    FOR j IN 1..t_periodes.COUNT LOOP

      IF t_datums(i) BETWEEN t_periodes(j).begindatum
                      AND t_periodes(j).einddatum THEN

      -- DIT MACHEERT NIET :'(
      SELECT * INTO t_periode_minste_opnames(teller)
      FROM t_periodes(j);

      teller := teller + 1;

      END IF;

    END LOOP;

  END LOOP;

END PERIODE_MINSTE_OPNAMES;