Dynamiczne zapytanie dla PIVOT w klauzuli

Coś takiego:

VARIABLE cur REFCURSOR;

DECLARE
  dates VARCHAR2(4000);
  start_date DATE := DATE '2017-09-18';
  end_date   DATE := DATE '2017-09-19';
BEGIN
  SELECT LISTAGG(
           'DATE ''' || TO_CHAR( dt, 'YYYY-MM-DD' )
           || ''' AS "' || TO_CHAR( dt, 'FMDY-DD' ) || '"',
           ','
         ) WITHIN GROUP ( ORDER BY dt )
  INTO   dates
  FROM   (
    SELECT start_date + LEVEL - 1 AS dt
    FROM   DUAL
    CONNECT BY LEVEL <= end_date - start_date + 1
  );

  OPEN :cur FOR
  'SELECT * FROM (
     SELECT t.*,
            MIN( start_date ) OVER ( PARTITION BY prod_id ) AS min_start_date,
            SUM( tot_hours  ) OVER ( PARTITION BY prod_id ) AS prod_tot_hours
     FROM   prod_timings t
     WHERE  start_date BETWEEN :1 AND :2
   )
   PIVOT (
     SUM( tot_hours )
     FOR start_date IN (' || dates || ')
   )
   ORDER BY prod_id'
   USING start_date, end_date;
END;
/

PRINT cur;