如将字符串‘张三,李四,王五,赵六,'转换成
1. 张三
2.李四
3.王五
4.赵六
REGEXP_SUBSTR
查询语句：
WITH TEST AS (SELECT ‘张三,李四,王五,赵六,' AS STR FROM DUAL)
SELECT DISTINCT REGEXP_SUBSTR(STR, '[^,]+', 1, LEVEL)
FROM TEST
CONNECT BY LEVEL<=LENGTH(STR)-LENGTH(REGEXP_REPLACE(STR,',',''))+1