Äntligen kom jag på det här svaret
WITH CTE AS (SELECT 'a,b,c,d,e' temp, 1 slno FROM DUAL
UNION
SELECT 'f,g' temp, 2 slno FROM DUAL
UNION
SELECT 'h' temp, 3 slno FROM DUAL)
SELECT TRIM(REGEXP_SUBSTR(temp, '[^,]+', 1, level)), slno
FROM CTE
CONNECT BY level <= REGEXP_COUNT(temp, '[^,]+')
AND PRIOR slno = slno
AND PRIOR DBMS_RANDOM.VALUE IS NOT NULL