自定义聚集函数，字符串SUM()出现乱码

[jzc376599425]

代码如下：

--创建Type
CREATE OR REPLACE  TYPE T_LINK AS OBJECT ( 
STR VARCHAR2(30000), 
STATIC FUNCTION ODCIAGGREGATEINITIALIZE(SCTX IN OUT T_LINK) RETURN NUMBER, 
MEMBER FUNCTION ODCIAGGREGATEITERATE(SELF IN OUT T_LINK, VALUE IN NVARCHAR2) RETURN NUMBER, 
MEMBER FUNCTION ODCIAGGREGATETERMINATE(SELF IN T_LINK, RETURNVALUE OUT NVARCHAR2, FLAGS IN NUMBER) RETURN NUMBER, 
MEMBER FUNCTION ODCIAGGREGATEMERGE(SELF IN OUT T_LINK, CTX2 IN T_LINK) RETURN NUMBER 
) 
/
--创建Body
CREATE OR REPLACE  TYPE BODY T_LINK IS 
STATIC FUNCTION ODCIAGGREGATEINITIALIZE(SCTX IN OUT T_LINK) RETURN NUMBER IS 
BEGIN 
SCTX := T_LINK(NULL); 
RETURN ODCICONST.SUCCESS; 
END; 

MEMBER FUNCTION ODCIAGGREGATEITERATE(SELF IN OUT T_LINK, VALUE IN NVARCHAR2) RETURN NUMBER IS 
BEGIN 
SELF.STR := SELF.STR ||','|| VALUE; 
RETURN ODCICONST.SUCCESS; 
END; 
 
MEMBER FUNCTION ODCIAGGREGATETERMINATE(SELF IN T_LINK, RETURNVALUE OUT NVARCHAR2, FLAGS IN NUMBER) RETURN NUMBER IS 
BEGIN 
RETURNVALUE := ltrim(rtrim(SELF.STR,','),','); 
RETURN ODCICONST.SUCCESS;
END; 

MEMBER FUNCTION ODCIAGGREGATEMERGE(SELF IN OUT T_LINK, CTX2 IN T_LINK) RETURN NUMBER IS 
BEGIN 
NULL; 
RETURN ODCICONST.SUCCESS; 
END; 
END; 
/
--创建Function
CREATE OR REPLACE  FUNCTION F_LINK(P_STR NVARCHAR2) RETURN NVARCHAR2
PARALLEL_ENABLE AGGREGATE USING T_LINK; 
/

一切都OK，但是用查询语句：

SELECT F_LINK(COL1) FROM TEST

查询出来的结果有乱码呢，我看了下是因为“,”的原因。把“SELF.STR := SELF.STR ||','|| VALUE; ”改成“SELF.STR := SELF.STR || VALUE; ”后，字符串连接又正常，大神们能不能支支招啊？？？