SQL函数：WMSYS.WM_CONCAT行转列详解数据库

select t.rank, t.Name from t_menu_item t;

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

select t.rank, WMSYS.WM_CONCAT(t.Name) TIME From t_menu_item t GROUP BY t.rank;

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

例子如下：

SQL> create table idtable (id number,name varchar2(30));

Table created

SQL> insert into idtable values(10,’ab’);

1 row inserted

SQL> insert into idtable values(10,’bc’);

1 row inserted

SQL> insert into idtable values(10,’cd’);

1 row inserted

SQL> insert into idtable values(20,’hi’);

1 row inserted

SQL> insert into idtable values(20,’ij’);

1 row inserted
SQL> insert into idtable values(20,’mn’);

1 row inserted

SQL> select * from idtable;

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

6 rows selected
SQL> select id,wmsys.wm_concat(name) name from idtable
2 group by id;

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

SQL> select id,wmsys.wm_concat(name) over (order by id) name from idtable;

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

6 rows selected

SQL> select id,wmsys.wm_concat(name) over (order by id,name) name from idtable;

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

6 rows selected

个人觉得这个用法比较有趣.

SQL> select id,wmsys.wm_concat(name) over (partition by id) name from idtable;

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

6 rows selected

SQL> select id,wmsys.wm_concat(name) over (partition by id,name) name from idtable;

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,pName) VALUES (1,’市场部’);
INSERT INTO tab_name2(ID,pName) VALUES (2,’研发部’);
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 cNamepName

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;