SELECT  REGEXP_SUBSTR (str, '[^,]+', 1, 1)    AS Col1
,       REGEXP_SUBSTR (str, '[^,]+', 1, 2)    AS Col2
,       REGEXP_SUBSTR (str, '[^,]+', 1, 3)    AS Col3
,       REGEXP_SUBSTR (str, '[^,]+', 1, 4)    AS Col4
FROM    table_x
;