麻烦帮忙看个sql解决办法

麻烦帮忙看个sql
SELECT MAX(SUBSTR(SYS_CONNECT_BY_PATH(COLUMN_NAME, ','), 2)) COL
  INTO VAR_STRING
  FROM (SELECT COLUMN_NAME, COLUMN_ID
  FROM USER_TAB_COLUMNS
  WHERE TABLE_NAME = V_TABLE_NAME)
  START WITH COLUMN_ID = 1
  CONNECT BY COLUMN_ID = ROWNUM;
  RETURN VAR_STRING;

[解决办法]
等同于...
select wm_contat(字段名) from yourtable;