Oracle 10g WM_CONCAT行转列函数用法及注意点

 

WM_CONCAT(colName)为Oracle 10g中行数据转列数据的内置函数,执行效果如下

表T

   A    B

------------

   1    2

   1    3

   1    4

   2    1

   2    3

执行语句 :

SELECT A, WM_CONCAT(B) B FROM T GROUP BY A

执行结果:

   A    B

---------------

   1    2,3,4

   2    1,3

 

注意:

  当在包体内使用行转列时,WM_CONCAT(colName)可以使用,但WM_CONCAT(DISTINCT colName)会在包编译时会报错,

  例如,在某一包的某一存储过程中有如下语句:

 1 UPDATE D_LOWAREA L

 2    SET L.BYQXH = (SELECT /*+index(b)*/

 3                    WM_CONCAT(DISTINCT XH.XHMC)

 4                     FROM OLIVE.OL$_ASSOCIATIONS A,

 5                          PMSBI.F_SB_SBXX_BASIC  B,

 6                          PMSBI.D_XH             XH

 7                    WHERE A.A IN (L.PDBYQ1, L.PDBYQ2, L.PDBYQ3)

 8                      AND A.B = B.SBBH

 9                      AND B.XHDM != 'wz'

10                      AND B.XHDM = XH.XHDM);

11 COMMIT;

 

     编译时会报如下错误:

     PL/SQL:ORA-30482:DISTINCT option not allowed for this function.

 

解决方案:

  使用动态SQL(字符串中有单引号由两个单引号表示):

 1    EXECUTE IMMEDIATE 

 2    'UPDATE D_LOWAREA L

 3       SET L.BYQXH = (SELECT /*+index(b)*/

 4                       WMSYS.WM_CONCAT(DISTINCT XH.XHMC)

 5                        FROM OLIVE.OL$_ASSOCIATIONS A,

 6                             PMSBI.F_SB_SBXX_BASIC  B,

 7                             PMSBI.D_XH             XH

 8                       WHERE A.A IN (L.PDBYQ1, L.PDBYQ2, L.PDBYQ3)

 9                         AND A.B = B.SBBH

10                         AND B.XHDM != ''wz''

11                         AND B.XHDM = XH.XHDM)';

12     COMMIT;

 

PS:Oracle 11g以上版本可以用LISTAGG实现行转列,写法如下:

SELECT A, LISTAGG(B, ',') WITHIN GROUP(ORDER BY B) B FROM T GROUP BY A

 

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