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


--------------------------------
我們通過 10g 所提供的 WMSYS.WM_CONCAT 函式即可以完成 行轉列的效果


    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
個人覺得這個用法比較有趣.
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、自定義行數實現行列轉換：
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,'網易');
INSERT INTO tab_name2(ID,pName) VALUES (1,'研發部');
INSERT INTO tab_name2(ID,pName) VALUES (1,'市場部');
INSERT INTO tab_name2(ID,pName) VALUES (2,'研發部');
INSERT INTO tab_name2(ID,pName) VALUES (2,'平臺架構');
INSERT INTO tab_name2(ID,pName) VALUES (3,'研發部');
COMMIT;
期望結果：
ID             cName                        pName               
1                 百度                     研發部,市場部
2                 Google                 研發部
3                  網易                     研發部,平臺架構
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:使用自定義函式
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;
 
轉自百度空間