oracle12 listagg 与 wm_concat行列转换

Posted 2020-10-19 听说睡觉会变白

11gr2和12C上已经摒弃了wm_concat函数，当时我们很多程序员在程序中确使用了该函数，导致程序出现错误，为了减轻程序员修改程序的工作量，只有通过手工创建个wm_concat函数，来临时解决该问题，但是注意，即使创建了该函数，在使用的过程中，也需要用to_char(wm_concat())方式，才能完全替代之前的应用。
一.解锁wmsys用户

alter user wmsys account unlock;

二.创建包、包体和函数
以wmsys用户登录数据库，执行下面的命令

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 ;  
/

三.创建同义词并授权

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;

或者使用listagg函数

以下为类比方法

select deptno, listagg(ename,‘,‘) within group(order by ename)
from scott.emp 
group by deptno

    DEPTNO PATH
---------- --------------------------------------------------------------------------------
 10 CLARK,KING,MILLER
 20 ADAMS,FORD,JONES,SCOTT,SMITH
 30 ALLEN,BLAKE,JAMES,MARTIN,TURNER,WARD

select deptno,wm_concat(ename) as path
from scott.emp
group by deptno

    DEPTNO PATH
---------- --------------------------------------------------------------------------------
 10 CLARK,MILLER,KING
 20 SMITH,FORD,ADAMS,SCOTT,JONES
 30 ALLEN,JAMES,TURNER,BLAKE,MARTIN,WARD