В основном вам нужно сгруппировать данные только по NUM_OFC_CODE,NUM_RO_CODE
(исключая TXT_MONTH, так как вы не хотите строки для каждого экземпляра TXT_MONTH), а затем использовать что-то вроде NVL(MAX(CASE WHEN TXT_MONTH='JAN' THEN 1 END), 0) as JAN
(используя функцию агрегирования, чтобы определить, будет ли записьсуществует или нет) и т. д.
Проще с использованием pivot:
-- Just some sampledata:
WITH LEG_OMBUDSMAN_NONMACT(NUM_OFC_CODE, NUM_RO_CODE, NUM_YEAR, TXT_MONTH) AS
(SELECT 1,1,2019, 'JAN' FROM dual union ALL
SELECT 1,1,2019, 'FEB' FROM dual)
-- Here starts the actual query:
SELECT NUM_OFC_CODE, NUM_RO_CODE
, NVL(JAN,0) AS JAN
, NVL(FEB,0) AS FEB
, NVL(MAR,0) AS MAR
, NVL(APR,0) AS APR
, NVL(MAY,0) AS MAY
, NVL(JUN,0) AS JUN
, NVL(JUL,0) AS JUL
, NVL(AUG,0) AS AUG
, NVL(SEP,0) AS SEP
, NVL(OCT,0) AS OCT
, NVL(NOV,0) AS NOV
, NVL(DEC,0) AS DEC
FROM LEG_OMBUDSMAN_NONMACT
pivot (MAX(1) FOR TXT_MONTH IN ('JAN' AS JAN,'FEB' AS FEB,'MAR' as MAR, 'APR' as APR, 'MAY' as MAY, 'JUN' as JUN, 'JUL' as JUL, 'AUG' as AUG, 'SEP' as SEP, 'OCT' as OCT, 'NOV' as NOV, 'DEC' as DEC ))
WHERE NUM_YEAR=2019