方法2：19c中手动创建wm_contact函数
参考如下链接：
https://blog.csdn.net/alicewang99/article/details/89945252

创建wm_concat函数
–首先使用dba账号登录oracle数据库
–解锁wmsys用户
alter user wmsys account unlock;

–并为wmsys用户授权，可根据需要授权，不建议授权所有权限
grant all privileges to wmsys;

–如果不知道wmsys用户的密码，可以修改其密码
alter user wmsys identified by 123456;

–使用wmsys用户登录数据库
conn wmsys/123456

–在wmsys下创建可用的wm_concat函数，直接执行以下语句
–定义类型
CREATE OR REPLACE TYPE WM_CONCAT_IMPL AS OBJECT
(
CURR_STR VARCHAR2(32767),
STATIC FUNCTION ODCIAGGREGATEINITIALIZE(SCTX IN OUT WM_CONCAT_IMPL) RETURN NUMBER,
MEMBER FUNCTION ODCIAGGREGATEITERATE(SELF IN OUT WM_CONCAT_IMPL,
P1 IN VARCHAR2) RETURN NUMBER,
MEMBER FUNCTION ODCIAGGREGATETERMINATE(SELF IN WM_CONCAT_IMPL,
RETURNVALUE OUT VARCHAR2,
FLAGS IN NUMBER)
RETURN NUMBER,
MEMBER FUNCTION ODCIAGGREGATEMERGE(SELF IN OUT WM_CONCAT_IMPL,
SCTX2 IN WM_CONCAT_IMPL) RETURN NUMBER
);
/

–定义类型body:
CREATE OR REPLACE TYPE BODY WM_CONCAT_IMPL
IS
STATIC FUNCTION ODCIAGGREGATEINITIALIZE(SCTX IN OUT WM_CONCAT_IMPL)
RETURN NUMBER
IS
BEGIN
SCTX := WM_CONCAT_IMPL(NULL) ;
RETURN ODCICONST.SUCCESS;
END;
MEMBER FUNCTION ODCIAGGREGATEITERATE(SELF IN OUT WM_CONCAT_IMPL,
P1 IN VARCHAR2)
RETURN NUMBER
IS
BEGIN
IF(CURR_STR IS NOT NULL) THEN
CURR_STR := CURR_STR || ‘,’ || P1;
ELSE
CURR_STR := P1;
END IF;
RETURN ODCICONST.SUCCESS;
END;
MEMBER FUNCTION ODCIAGGREGATETERMINATE(SELF IN WM_CONCAT_IMPL,
RETURNVALUE OUT VARCHAR2,
FLAGS IN NUMBER)
RETURN NUMBER
IS
BEGIN
RETURNVALUE := CURR_STR ;
RETURN ODCICONST.SUCCESS;
END;
MEMBER FUNCTION ODCIAGGREGATEMERGE(SELF IN OUT WM_CONCAT_IMPL,
SCTX2 IN WM_CONCAT_IMPL)
RETURN NUMBER
IS
BEGIN
IF(SCTX2.CURR_STR IS NOT NULL) THEN
SELF.CURR_STR := SELF.CURR_STR || ‘,’ || SCTX2.CURR_STR ;
END IF;
RETURN ODCICONST.SUCCESS;
END;
END;
/
–自定义行变列函数:
CREATE OR REPLACE FUNCTION wm_concat(P1 VARCHAR2)
RETURN VARCHAR2 AGGREGATE USING WM_CONCAT_IMPL ;
/

–创建完成，给其创建同义词及授权，以供其他用户能正常使用。
create public synonym WM_CONCAT_IMPL for wmsys.WM_CONCAT_IMPL
/
create public synonym wm_concat for wmsys.wm_concat
/

grant execute on WM_CONCAT_IMPL to public
/
grant execute on wm_concat to public
/