u010463375
u010463375
采纳率50%
2013-07-02 03:39 阅读 5.5k

求帮助,oracle数据库,查询出每个地方的最新时间的那一条数据

select p.* from (select rownum as 序号 ,n.* from (select sitename as 站点名称, RecordTime as 记录时间 ,decode(avg(case item when 211 then value else null end),0,'0.00000',trim(to_char(avg(case item when 211 then value else null end),'99999999999990.99999'))) "SO2(mg/m3)"
from(select s.sitename,m.* from air_temphourdata m left join site s on m.sitecode=s.sitecode where m.SiteCode in ('34656-31102001','34656-31102006'))
group by sitename,Recordtime having to_char(Recordtime,'yyyymmddhhmmss')=MAX(to_char(Recordtime,'yyyymmddhhmmss'))
order by RecordTime desc ) n )p where p.序号 between 1 and 15 只查询出每个站点最大时间的那一条
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1条回答 默认 最新

  • 已采纳
    p456789sc0324 p456789sc0324 2013-07-02 07:22

    select p.* from
    (select rownum as 序号 ,n.* from
    (select sitename as 站点名称, max(RecordTime) as 记录时间 ,
    decode(avg(case item when 211 then value else null end),0,'0.00000',
    trim(to_char(avg(case item when 211 then value else null end),'99999999999990.99999'))) "SO2(mg/m3)" FROM
    (select s.sitename,m.* from air_temphourdata m
    left join site s on m.sitecode=s.sitecode
    where m.SiteCode in ('34656-31102001','34656-31102006'))
    group by sitename
    ) order by 站点名称 desc ) n )p
    where p.序号 between 1 and 15

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