在12c上使用wm_concat

WM_CONCAT是Oracle内部的一个函数，在不同版本，这个函数的返回值是不一样的。Oracle对这个函数也没有明确说明，当然也不建议使用。在12c上这个函数就更不用说了，如果要用，最好自己写个函数来实现，因为升级可能会因为这个遇到问题，之后还支持不支持这个函数，还是个问题。如果急用，下面的可作为一个Workaround。

CREATE OR REPLACE TYPE WMSYS.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  
);  
/  
 
 
CREATE OR REPLACE TYPE BODY WMSYS.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;  
/  

CREATE OR REPLACE FUNCTION WMSYS.WM_CONCAT(P1 VARCHAR2)  
RETURN VARCHAR2 AGGREGATE USING WM_CONCAT_IMPL ;  
/  

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  
/