當我們的程序需要連接12C數據庫時，原本使用wm_concat函數的地方會出現報錯，這是由於12C已經摒棄了wm_concat這個函數，可以采取的辦法有使用listagg函數代替wm_concat函數，但是程序中所有涉及wm_concat函數的地方都得改成listagg函數的寫法，所以為了減小修改程序的工作量，可以通過手工創建wm_concat函數來解決這個問題。

一、用sys用戶以SYSDBA身份登錄數據庫，執行以下命

CREATE OR REPLACE TYPE WM_CONCAT_IMPL AS OBJECT
-- AUTHID CURRENT_USER 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
);
/
 

--定義類型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;
/
 

--自定義函數列表
CREATE OR REPLACE FUNCTION wm_concat(P1 VARCHAR2)
RETURN VARCHAR2 AGGREGATE USING WM_CONCAT_IMPL ;
/

二、創建同義詞並授權

create public synonym WM_CONCAT_IMPL for sys.WM_CONCAT_IMPL
/
create public synonym wm_concat for sys.wm_concat
/

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

在Oracle12C數據庫創建wm_concat函數