[转]用WMSYS.WM_CONCAT()函数实现行列转换

SQL> select version from v$instance;

VERSION
-----------------
10.2.0.1.0

SQL>
SQL> create table IDTABLE
2 (
3    id number,
4    val varchar2(20)
5 )
6 ;

Table created

SQL>
SQL> insert into IDTABLE (ID, VAL)
2 values (10, 'abc');

1 row inserted
SQL> insert into IDTABLE (ID, VAL)
2 values (10, 'abc');

1 row inserted
SQL> insert into IDTABLE (ID, VAL)
2 values (10, 'def');

1 row inserted
SQL> insert into IDTABLE (ID, VAL)
2 values (10, 'def');

1 row inserted
SQL> insert into IDTABLE (ID, VAL)
2 values (20, 'ghi');

1 row inserted
SQL> insert into IDTABLE (ID, VAL)
2 values (20, 'jkl');

1 row inserted
SQL> insert into IDTABLE (ID, VAL)
2 values (20, 'mno');

1 row inserted
SQL> insert into IDTABLE (ID, VAL)
2 values (20, 'mno');

1 row inserted

SQL> select id,val from idtable;

        ID VAL
---------- --------------------
        10 abc
        10 abc
        10 def
        10 def
        20 ghi
        20 jkl
        20 mno
        20 mno

8 rows selected

SQL> commit;

Commit complete

SQL>
SQL> SELECT ID, WMSYS.WM_CONCAT(VAL) AS ENAMES
2    FROM IDTABLE
3   GROUP BY ID;

        ID ENAMES
---------- --------------------------------------------------------------------------------
        10 abc,abc,def,def
        20 ghi,jkl,mno,mno

SQL>
SQL> SELECT ID, WMSYS.WM_CONCAT(DISTINCT VAL) AS ENAMES
2    FROM IDTABLE
3   GROUP BY ID
4   ORDER BY ID;

        ID ENAMES
---------- --------------------------------------------------------------------------------
        10 abc,def
        20 ghi,jkl,mno

SQL>
SQL> SELECT ID, VAL, WMSYS.WM_CONCAT(VAL) OVER(PARTITION BY ID) AS ENAMES
2    FROM IDTABLE
3   ORDER BY ID;

        ID VAL               ENAMES
---------- -------------------- --------------------------------------------------------------------------------
        10 abc                abc,abc,def,def
        10 abc                abc,abc,def,def
        10 def                abc,abc,def,def
        10 def                abc,abc,def,def
        20 ghi                ghi,jkl,mno,mno
        20 jkl                 ghi,jkl,mno,mno
        20 mno               ghi,jkl,mno,mno
        20 mno               ghi,jkl,mno,mno

8 rows selected

SQL>
SQL> SELECT ID, VAL, WMSYS.WM_CONCAT(VAL) OVER(ORDER BY ID, VAL) AS ENAMES
2    FROM IDTABLE
3   ORDER BY ID;

        ID VAL               ENAMES
---------- -------------------- --------------------------------------------------------------------------------
        10 abc                abc,abc
        10 abc                abc,abc
        10 def                abc,abc,def,def
        10 def                abc,abc,def,def
        20 ghi                abc,abc,def,def,ghi
        20 jkl                 abc,abc,def,def,ghi,jkl
        20 mno               abc,abc,def,def,ghi,jkl,mno,mno
        20 mno               abc,abc,def,def,ghi,jkl,mno,mno

8 rows selected

SQL>

from：http://blog.csdn.net/zhpsam109/archive/2007/12/04/1917011.aspx

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