原始字符串为'aa,bb,cc',分隔符为','
SELECT TRIM(substr(txt, instr(txt, ',', 1, LEVEL) + 1, instr(txt, ',', 1, LEVEL + 1) - instr(txt, ',', 1, LEVEL) - 1)) AS file_name FROM (SELECT ',' || 'aa,bb,cc' || ',' txt FROM dual)CONNECT BY LEVEL <= length('aa,bb,cc') - length(REPLACE('aa,bb,cc', ',', '')) + 1结果为：
aabbcc