Select mit Case

   SELECT
    AVG(
        CASE  WHEN T2.tkaf_LIEFD < T1.tkaf_LIEFD THEN 
           0 
        ELSE 
            KNA_DATUM_DIFF_OHNE_SFT(((((((LPAD(TO_CHAR(TRUNC(TO_NUMBER(TO_CHAR(T1.tkaf_LIEFD ,'DD')) ) ),2 ,'0') || LPAD(TO_CHAR(TRUNC(TO_NUMBER(TO_CHAR(T1.tkaf_LIEFD 
            ,'MM')) ) ),2 ,'0')) || TO_CHAR(TRUNC(TO_NUMBER(TO_CHAR(T1.tkaf_LIEFD 
            ,'YYYY')) ) )) || '-') || LPAD(TO_CHAR(TRUNC(TO_NUMBER(TO_CHAR(T2.tkaf_LIEFD 
            ,'DD')) ) ),2 ,'0')) || LPAD(TO_CHAR(TRUNC(TO_NUMBER(TO_CHAR(T2.tkaf_LIEFD 
            ,'MM')) ) ),2 ,'0')) || TO_CHAR(TRUNC(TO_NUMBER(TO_CHAR(T2.tkaf_LIEFD 
            ,'YYYY')) ) ))) 
        END
        )  LIEFERZEIT_IN_TAGEN
    , SUM(SCHEMA.F_FUNKTIONSNAME('WEL',T2.tkaf_NR,'SUM')) WEL_WERT
    , SUM(SCHEMA.F_FUNKTIONSNAME('WEL',T2.tkaf_NR,'ANZ')) WEL_ANZ_POS
    , SUM(SCHEMA.F_FUNKTIONSNAME('BEL',T1.tkaf_NR,'SUM')) BEL_BESTELLWERT
    , SUM(SCHEMA.F_FUNKTIONSNAME('BEL',T1.tkaf_NR,'ANZ')) BEL_ANZ_POS
    FROM SCHEMA.FA T1
       , SCHEMA.FA T2
       , SCHEMA.LB T3
       , SCHEMA.KU T4
    WHERE T1.TKAF_ART      = T2.TKAF_ABART 
      AND T1.TKAF_NR       = T2.TKAF_ABNR 
      AND T1.FA_KDNR_id = T2.FA_KDNR_id 
      AND T3.LFBD_NO       = T1.TKAF_LFBED 
      AND T4.DNUK_ID       = T1.FA_KDNR_id 
      AND T4.DNUK_LFD      = T1.FA_KDNR_KU_LFD 
      AND T1.TKAF_ART      = 'BEL' 
      AND T2.TKAF_ART      = 'WEL' 
      AND T2.TKAF_LIEFD    BETWEEN TO_DATE('01.01.1900','DD.MM.YYYY') AND TO_DATE('31.12.1900','DD.MM.YYYY')
      AND T1.FA_rndk_id = 47110815
      AND T2.TKAF_diah     BETWEEN 2 AND 12;


CREATE OR REPLACE FORCE VIEW SCHEMA.V_XYZ_PLANUNG_KW
AS 
SELECT   FILIALE
       , ABTEILUNG
       , JAHR
       , LJ_KW,
            (CASE ABTEILUNG
                WHEN 24
                   THEN SUM (ROUND (NVL (XYZ_PLANUMSATZ_BRUTTO, 0) * 100 / 107))
                WHEN 25
                   THEN SUM (ROUND (NVL (XYZ_PLANUMSATZ_BRUTTO, 0) * 100 / 107))
                ELSE SUM (ROUND (NVL (XYZ_PLANUMSATZ_BRUTTO, 0) * 100 / 119))
             END
            ) HUBABUBBA
       FROM XYZ_PLANUMSATZ_BRUTTO
   GROUP BY FELD1, FELD2, JAHR, KALENDERWOCHE
   ORDER BY FELD1, FELD2, JAHR, KALENDERWOCHE;