Oracle中将自符串按分割符转换为记录集

SELECT SUBSTR(MAIN_STRING,
POSITION_FROM + 1,
POSITION_TO - POSITION_FROM - 1) AS RESULTSET

FROM (SELECT MAIN_STRING,
DECODE(ROWNUM - 1,
0,
0,
INSTR(MAIN_STRING, ',', 1, ROWNUM - 1)) POSITION_FROM,
INSTR(MAIN_STRING, ',', 1, ROWNUM) POSITION_TO
FROM (SELECT '111,222,333,444' || ',' AS MAIN_STRING FROM DUAL)
CONNECT BY LEVEL <= LENGTH(MAIN_STRING))
WHERE POSITION_TO > 0