Table update by pressing a button

Question

hello,
I would like to update all fields from r_wep where wep.gln is empty and field lieferdatum is today-100 days and r_warengru_nummer is 1,2,4 or 6 after pressing a button in the form.
It should be filled with the field gln from r_kunde if the field r_kunde.Lieferantenart=1. If I do the SQL Statement below I get a message select supplies more
than one line. what is wrong?
update r_wep
set gln=
(SELECT R_KUNDE.GLN
FROM R_KUNDE, r_wep
WHERE (LIEFERANTENART=1
AND R_WEP.KUNDE=R_KUNDE.NUMMER)
where
GLN IS NULL
AND LIEFERDATUM>SYSDATE-100
aND (R_WARENGRU_NUMMER=1
OR R_WARENGRU_NUMMER=2
OR R_WARENGRU_NUMMER=4
OR R_WARENGRU_NUMMER=6)
;

Answer 1

Seems to be nearly correct, try
update r_wep set
  gln=(SELECT R_KUNDE.GLN
         FROM R_KUNDE
        WHERE LIEFERANTENART=1
          AND R_KUNDE.NUMMER=r_wep.KUNDE
where GLN IS NULL
  AND LIEFERDATUM>SYSDATE-100
  aND (   R_WARENGRU_NUMMER=1
       OR R_WARENGRU_NUMMER=2
       OR R_WARENGRU_NUMMER=4
       OR R_WARENGRU_NUMMER=6
      );not tested