oracle 使用REGEXP_SUBSTR正則表達式拆分字符串

SELECT REGEXP_SUBSTR ('first field, second field , third field', '[^,]+', 1,rownum)
    FROM DUAL
    CONNECT BY ROWNUM <=
   LENGTH ('first field, second field , third field') - LENGTH (REPLACE ('first field, second field , third field', ',', ''))+1;

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first field
second field
third field