如何从三张桌子中获取价值？

Question

我有三张这样的表：

-drivingtime
  +id
  +starttime
  +stoptime
-fuel
  +id
  +timestamp
  +fuellevel
-addingfuel
  +id
  +timestamp
  +fueladding

我希望在同一个屏幕上显示启动时间，停止时间，燃油液位（启动时间），燃油液位（停止时间）。那我到底要做什么呢？我搜索谷歌的解决方案，但其他问题是完全不同的。

我试过了：

SELECT startTime and stopTime 
from tblDrivingTime d 
left join tblFuel f on d.startTime = f.timestamp 
left join tblFuel f on d.stopTime = f.timestamp 
left join tblDoXang x on d.startTime < x.timestamp < d.stopTime

Answer 1

这是一个返回您要查找的结果的查询：

SELECT DT.starttime
    ,DT.stoptime
    ,FB.fuellevel AS `startfuellevel`
    ,FE.fuellevel AS `stopfuellevel`
    ,(SELECT COUNT(AF.id)
     FROM addingfuel AF
     WHERE AF.timestamp BETWEEN DT.starttime AND DT.stoptime) AS `nbaddingevents
FROM drivingtime DT
INNER JOIN fuel FB ON FB.timestamp = DT.starttime
INNER JOIN fuel FE ON FE.timestamp = DT.stoptime

希望这会对你有所帮助。