在oracle 11中使用连接字符串的order by子句

Question

我在连接列上使用order by子句时遇到错误。

“不一致的数据类型：预期 - 得到了CLOB”

功能：

create or replace FUNCTION LIST_PNUM (CID  in NUMBER) RETURN CLOB  
IS 
    l_text clob := NULL;
BEGIN 
  FOR cur_rec IN (SELECT C.E_DEVICE FROM CUSTOMER_PCN A, CP_DEVICE B, ET_DEVICE C WHERE A.C_ID = CID AND A.CP_ID = B.CP_ID AND B.ET_DEVICE_ID=C.ET_DEVICE_ID AND ROWNUM <= 250 ORDER BY C.E_DEVICE ) 
  LOOP     
     l_text := l_text || ',' || cur_rec.e_device;  
  END LOOP;  
  RETURN LTRIM(l_text, ',');  
END LIST_PNUM;

查看：

CREATE OR REPLACE VIEW "MYView" ("P_ID", "E_DEVICE") AS 
select p.p_id, LIST_PNUM(c.customer_id) AS e_device       
from Table .....  where Condition;

选择声明：

select p_id, e_device from MYView order by e_device desc;

错误：

  

“不一致的数据类型：预期 - 得到了CLOB”