资料形态：

希望算出USN栏位后面逗号分隔数据的sum值，期望结果是5.

SQL如下：

SELECT SUM(A)

  FROM (SELECT REGEXP_SUBSTR(sn, '[^,]+', 1, 2) AS a

           FROM INFO

          WHERE REGEXP_LIKE(sn, '[^,]+')

            AND ID = '5000012028'

            AND IDITEM = '20') b;