切勿使用WM_CONCAT
. Read 为什么不在Oracle中使用WM_CONCAT函数?
看这个主题https://stackoverflow.com/a/28758117/3989608.
它没有记录,任何依赖于它的应用程序WM_CONCAT
一旦升级到将无法工作12c
因为它已经从最新的12c版本中删除了。
有很多方法可以做字符串聚合,取决于数据库版本。请参阅下面的几个示例:
11gR2
Use LIASTAGG
:
SQL> SELECT grp,
2 listagg(command, ',') WITHIN GROUP(
3 ORDER BY seq) command
4 FROM t
5 GROUP BY grp;
GRP COMMAND
--- --------------------------------------------------------------------------------------------
ONE <?xml version=1.0 encoding=UTF-8?>,<message1>MESSAGE</message1>,<message2>MESSAGE</message2>
TWO <?xml version=1.0 encoding=UTF-8?>,<message2>MESSAGE</message2>,<message9>MESSAGE</message9>
SQL>
9i 及更高版本
Use ROW_NUMBER()
and SYS_CONNECT_BY_PATH
:
SQL> SELECT grp,
2 LTRIM(MAX(SYS_CONNECT_BY_PATH(command,','))
3 KEEP (DENSE_RANK LAST ORDER BY seq),',') command
4 FROM (SELECT grp,
5 command,
6 seq,
7 ROW_NUMBER() OVER (PARTITION BY grp ORDER BY seq) AS curr,
8 ROW_NUMBER() OVER (PARTITION BY grp ORDER BY seq) -1 AS prev
9 FROM t)
10 GROUP BY grp
11 CONNECT BY prev = PRIOR curr AND grp = PRIOR grp
12 START WITH curr = 1;
GRP COMMAND
--- --------------------------------------------------------------------------------------------
ONE <?xml version=1.0 encoding=UTF-8?>,<message1>MESSAGE</message1>,<message2>MESSAGE</message2>
TWO <?xml version=1.0 encoding=UTF-8?>,<message2>MESSAGE</message2>,<message9>MESSAGE</message9>
SQL>