Question

这段代码给了我一个很好的结果。但我想在另一个表中添加一些字段，我不知道在哪里添加additioanal WHERE代码......

select day, sum(diff) as total_diff
from (
select sub_meterID, date(`date`) as day, max(value) - min(value) as diff
from `sub_meter_data`
where date(`date`) > '2012-10-01'
   and sub_meterID in ('58984','58985','58986','58987')
group by sub_meterID, date(`date`)
) a
group by day

我需要匹配的其他字段是：

othertable.meterID = sub_meter_data.sub_meterID

moretable.meterID = othertableID

Answer 1

select day, sum(diff) as total_diff
from (
select t1.sub_meterID, date(t1.`date`) as day, max(t1.value) - min(t1.value) as diff
from `sub_meter_data` t1
JOIN othertable t2 ON t1.sub_meterID=t2.meterID
JOIN moretable t3 ON t2.ID=t3.meterID
where date(t1.`date`) > '2012-10-01'
   and t1.sub_meterID in ('58984','58985','58986','58987')
group by t1.sub_meterID, date(t1.`date`)
) a
group by day

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MySQL使用子选择查询添加多个WHERE

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