ORA-00932：数据类型不一致：预期-获得CLOB00932。00000-在将XMLAGG与PIVOT结合使用时，“数据类型不一致：预期％s获得了％s”

Question

使用XMLAGG函数组合多个值并最终在结果上应用PIVOT时，出现错误“数据类型不一致：预期的％s得到了％s”。

我尝试删除PIVOT部分中的聚合函数（MAX，MIN等），当我删除PIVOT时，查询没有问题。 PIVOT是否不适用于XMLAGG列？

SELECT *
FROM
  (SELECT pr.id PR_ID,
    p.name PROJECT,
    df.name field,
    (SELECT (XMLAGG(XMLELEMENT (e, SUBSTR(s_value, - instr(reverse(s_value), '\') + 1)
      || '<eof>')).EXTRACT('//text()').GetClobVal())
    FROM pr_addtl_data pad2
    WHERE pad2.pr_id      = pr.id
    AND pad2.data_field_id=df.id
    ) "Files"
  FROM pr pr
  LEFT OUTER JOIN pr_addtl_data pad
  ON pr.id=pad.pr_id
  LEFT OUTER JOIN project p
  ON pr.project_id = p.id
  LEFT OUTER JOIN data_fields df
  ON pad.data_field_id=df.id
  WHERE df.name      IN ('Attached Files','Certificate of Audit Files')
  AND p.name LIKE 'Audit'
  AND pr.is_closed = 1
  GROUP BY pr.id,
    p.name,
    df.id,
    df.name
  ) PIVOT ( MAX("Files") FOR field IN ('Attached Files','Certificate of Audit Files') )