WITH my_data AS
     (SELECT   subpnlname
          FROM pspnlfield
         WHERE pnlname = :1 AND subpnlname <> ' '
      GROUP BY subpnlname)
SELECT   recname
    FROM pspnlfield, my_data
   WHERE pnlname = :1 OR pnlname = my_data.subpnlname
GROUP BY recname;

SELECT   recname
    FROM pspnlfield a
   WHERE pnlname = :1
      OR EXISTS (
            SELECT 'x'
                FROM pspnlfield b
               WHERE pnlname = :1
                 AND subpnlname <> ' '
                 AND a.pnlname = b.subpnlname)
GROUP BY recname;