select * from (select * from (select companyid,distinct devcode,datetimes,watt,var from test order by datetimes desc) where rownum<3));
试试行不行
试试行不行
解决方案 »
- Oracle中空字符串等于NULL值的处理,带来很多痛苦啊,为什么要这样呢?求解!
- ORA-12514 监听程序当前无法识别连接描述符中的服务
- Oracle的汇总查询问题
- oracle 数据库迁移问题 据库A 里a表 到 数据库B里b表 (两表结构不同)
- ORACLE隐式游标与显式游标有何区别?
- 关于Dynamic SQL 的问题,高手请进(在线等)
- oracle :监听程序无法启动专用服务器
- 跪着在线等,关于oracle not available问题
- 主数据库服务器(运行在ARCHIVELOG下)数据文件丢失,将丢失的数据文件OFFLINE,重建热备用数据库(STANDBY
- 双网切换问题。高分相送,在线等待。
- oracle9.2.0.1中blob数据操作问题
- 高分请教,如何在PB6.5中存取ORACLE的BLOB字段?急急急...
from (select max(DATETIMES) DATETIMES
from tablename) A,
tablename B
where b.DATETIMES=a.DATETIMES
union
select b.*
from
(select max(b.DATETIMES)
from (select b.DATETIMES,b.DEVCODE
from (select max(DATETIMES) DATETIMES
from tablename) A,
tablename B
where b.DATETIMES=a.DATETIMES) A,
tablename B
where b.DATETIMES<a.DATETIMES
and b.DEVCODE<>a.DEVCODE) a,
tablename b
where a.DATETIMES=b.DATETIMES
sql>select companyid,devcode,datetimes,watt,var from
(select tablename.*,rank() over (partition by devcode order by datetimes desc) rk from tablename) where rk<=2;
where a.DEVCODE=b.DEVCODE and b.DATETIMES<=a.DATETIMES )<=2 ORDER BY DEVCODE,DATETIMES DESC
(select * from
(select a.*,lead(DEVCODE,1,null) over(order by datetimes desc) lead_DEVCODE from tab a order by DATETIMES desc)
where DEVCODE<>lead_DEVCODE)
where rownum<3