通过Oracle串联 [英] Concatenate Over Oracle

问题描述

这是样本表数据

Fruit   Number
Apple    1
Apple    2
Apple    3
Kiwi     6
Kiwi     10

我尝试将表的列值连接起来以获取以下信息

I try to concatenate the table column values to get the following

Fruit   Number
Apple    1-2-3
Kiwi     6-10

是否有查询此或存储过程的方法? 像Concatenate over(partition by)之类的东西，我对存储过程了解不多.谢谢！

Is there a way to query this or store procedure? Something like Concatenate over(partition by) , I don't know much about stored procedures. Thanks!

推荐答案

OP在Oracle 10g 上运行，并且在 11g第2版中引入了 LISTAGG strong>.

OP is on Oracle 10g, and LISTAGG was introduced in 11g Release 2.

因此，在不支持LISTAGG的Oracle版本 11g 之前，可以使用 ROW_NUMBER()和 SYS_CONNECT_BY_PATH 函数.

Therefore, in Oracle version prior to 11g where LISTAGG is not supported, you could use ROW_NUMBER() and SYS_CONNECT_BY_PATH functions.

SELECT fruit,
  LTRIM(MAX(SYS_CONNECT_BY_PATH(number,','))
  KEEP (DENSE_RANK LAST ORDER BY curr),',') AS fruits_agg
  FROM   (SELECT fruit,
                number,
                ROW_NUMBER() OVER (PARTITION BY fruit ORDER BY number) AS curr,
                ROW_NUMBER() OVER (PARTITION BY fruit ORDER BY number) -1 AS prev
         FROM   table_name)
  GROUP BY fruit
  CONNECT BY prev = PRIOR curr AND fruit = PRIOR fruit
 START WITH curr = 1;

注意

请勿使用WM_CONCAT，因为它是未记录的功能，并且已从12c版本中删除.

Never use WM_CONCAT since it is an undocumented feature and it has been removed from 12c version.

任何依赖于wm_concat功能的应用程序一旦升级到12c，将无法正常工作.从那以后，它已被删除.请参见为什么不在Oracle中使用WM_CONCAT函数?

Any application which has had been relying on wm_concat function will not work once upgraded to 12c. Since, it has been removed. See Why not use WM_CONCAT function in Oracle?

SQL> select banner from v$version where rownum = 1;

BANNER
----------------------------------------------------------------------------
Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production

SQL> SELECT object_name
  2  FROM dba_objects
  3  WHERE owner='WMSYS'
  4  AND object_name LIKE 'WM\_%' ESCAPE '\';

OBJECT_NAME
----------------------------------------------------------------------------
WM_REPLICATION_INFO
WM_RDIFF
WM_PERIOD
WM_PERIOD
WM_OVERLAPS
WM_MEETS
WM_LESSTHAN
WM_LDIFF
WM_INTERSECTION
WM_INSTALLATION
WM_GREATERTHAN
WM_EVENTS_INFO
WM_ERROR
WM_ERROR
WM_EQUALS
WM_DDL_UTIL
WM_DDL_UTIL
WM_CONTAINS
WM_COMPRESS_BATCH_SIZES
WM_COMPRESSIBLE_TABLES

20 rows selected.

SQL>

您将收到"无效的标识符"错误:

SQL> SELECT banner FROM v$version;

BANNER
----------------------------------------------------------------------------
Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
PL/SQL Release 12.1.0.1.0 - Production
CORE    12.1.0.1.0      Production
TNS for 64-bit Windows: Version 12.1.0.1.0 - Production
NLSRTL Version 12.1.0.1.0 - Production

SQL> SELECT deptno, wm_concat(ename) FROM emp;
SELECT deptno, wm_concat(ename) FROM emp
               *
ERROR at line 1:
ORA-00904: "WM_CONCAT": invalid identifier

因此，完全没有必要依赖未记录的功能，该功能在最新版本中不再可用.

Therefore, there is no point relying on an undocumented feature which is no more made available in latest versions.

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