Mysql里面的union与order by

Mysql里面的union与order by

一个示例

 (select

a.`monitortype`,a.`servername`,a.`monitortime`,a.`rio`,a.`wio`,a.`wuse`,a.`ruse`,a.`use` from skio a,portip b,hardware c where a.servername = b.server_ip and b.h_serverserial = c.h_serverserial and c.h_groupmonitor='test' and  a.MonitorTime>'2010-06-01 10:52:14' and a.MonitorTime < '2010-06-02 10:52:17' order by a.monitortime desc) union select * from (select a.`monitortype`,a.`servername`,a.`monitortime`,a.`rio`,a.`wio`,a.`wuse`,a.`ruse`,a.`use`  from skio a,mserver b where (a.servername = b.vwip or a.servername = b.vlip) and b.h_groupmonitor='test' and  a.MonitorTime>'2010-06-01 10:52:14' and a.MonitorTime < '2010-06-02 10:52:17' order by a.monitortime desc)  limit 0,50

以上的一条SQL语句

经过了一段UNION运算之后发现并没有按照我想要的 order by a.monitortime desc 进行排序处理。

解决办法：

Select * from

(select

a.`monitortype`,a.`servername`,a.`monitortime`,a.`rio`,a.`wio`,a.`wuse`,a.`ruse`,a.`use` from skio a,portip b,hardware c where a.servername = b.server_ip and b.h_serverserial = c.h_serverserial and c.h_groupmonitor='test' and  a.MonitorTime>'2010-06-01 10:52:14' and a.MonitorTime < '2010-06-02 10:52:17' order by a.monitortime desc)

as A union select * from ( select * from (select a.`monitortype`,a.`servername`,a.`monitortime`,a.`rio`,a.`wio`,a.`wuse`,a.`ruse`,a.`use`  from skio a,mserver b where (a.servername = b.vwip or a.servername = b.vlip) and b.h_groupmonitor='test' and  a.MonitorTime>'2010-06-01 10:52:14' and a.MonitorTime < '2010-06-02 10:52:17' order by a.monitortime desc) as B  limit 0,50

这样就可以了。即添加一个select * from 这样的一个东西。因为子集合里面的数据已作了排序了！