Oracle数据库合并行记录，WMSYS.WM_CONCAT 函數的用法

Oracle数据库合并行记录，WMSYS.WM_CONCAT 函數的用法

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1. selectt.rank,t.Namefromt_menu_itemt;

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

--------------------------------
我们通过 10g 所提供的 WMSYS.WM_CONCAT 函数即可以完成 行转列的效果

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

例子如下：

ID NAME
---------- ------------------------------
10 ab
10 bc
10 cd
20 hi
20 ij
20 mn

6 rows selected

ID NAME
---------- --------------------------------------------------------------------------------
10 ab,bc,cd
20 hi,ij,mn

ID NAME
---------- --------------------------------------------------------------------------------
10 ab,cd
10 ab,cd
20 ab,cd,hi,mn
20 ab,mn

6 rows selected

ID NAME
---------- --------------------------------------------------------------------------------
10 ab
10 ab,bc
10 ab,hi
20 ab,ij
20 ab,mn

6 rows selected

个人觉得这个用法比较有趣.

ID NAME
---------- --------------------------------------------------------------------------------
10 ab
10 bc
10 cd
20 hi
20 ij
20 mn

6 rows selected

ps:

wmsys.wm_concat、sys_connect_by_path、自定义行数实现行列转换：

CREATE TABLE tab_name(ID INTEGER NOT NULL PRIMARY KEY,cName VARCHAR2(20));
CREATE TABLE tab_name2(ID INTEGER NOT NULL,pName VARCHAR2(20));

INSERT INTO tab_name(ID,cName) VALUES (1,'百度');
INSERT INTO tab_name(ID,cName) VALUES (2,'Google');
INSERT INTO tab_name(ID,cName) VALUES (3,'网易');
INSERT INTO tab_name2(ID,pName) VALUES (1,'研发部');
INSERT INTO tab_name2(ID,'市场部');
INSERT INTO tab_name2(ID,pName) VALUES (2,'平台架构');
INSERT INTO tab_name2(ID,pName) VALUES (3,'研发部');
COMMIT;

期望结果：

ID cName pName

1 百度 研发部,市场部

2 Google 研发部

3 网易 研发部,平台架构

方法一:使用wmsys.wm_concat()

SELECT t1.ID,t1.cName,wmsys.wm_concat(t2.pName) FROM tab_name t1,tab_name2 t2 WHERE t1.ID=t2.ID GROUP BY t1.cName,t1.id;

方法二:使用sys_connect_by_path

select id,cName,ltrim(max(sys_connect_by_path(pName,',')),') from (select row_number() over(PARTITION by t1.id ORDER by cName) r,t1.*,t2.pName from tab_name t1,tab_name2 t2 where t1.id = t2.id)
start with r=1 CONNECT by prior r =r-1 and prior id = id group by id,cName order by id;

方法三:使用自定义函数

create or replace function coltorow(midId INT) RETURN VARCHAR2 is
Result VARCHAR2(1000);
begin
FOR cur IN (SELECT pName FROM tab_name2 t2 WHERE midId=t2.id) LOOP
RESULT:=RESULT||cur.pName||',';
END LOOP;
RESULT:=rtrim(RESULT,');
return(Result);
end coltorow;

SELECT t1.*,coltorow(t1.ID) FROM tab_name t1,tab_name2 t2 WHERE t1.ID=t2.ID GROUP BY t1.ID,t1.cname ORDER BY t1.ID;

（编辑：李大同）

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