mysql查询在平均时加入1个表中的3个查询

Question

我有 3 个非常大的表，每分钟记录一次值， 以下是这些表格的摘录。

我想获得这些表的1 天期间的每小时平均值，并根据时间加入它们，请注意 ph 和温度的记录时间之间有几秒钟的差距

表 PH（仅提取，此表非常大，包含超过 130,000 个值）

    ID      time                Ph

    72176   2013-04-06 03:29:34 7.58
    72177   2013-04-06 03:30:34 7.58
    72178   2013-04-06 03:31:34 7.54
    72179   2013-04-06 03:32:34 7.58
    72180   2013-04-06 03:33:34 7.58
    72181   2013-04-06 03:34:34 7.58
    72182   2013-04-06 03:35:34 7.54
    72183   2013-04-06 03:36:34 7.58
    72184   2013-04-06 03:37:34 7.54
    72185   2013-04-06 03:38:34 7.58
    72186   2013-04-06 03:39:34 7.58

表温度1（仅提取，此表非常大，有超过 130,000 个值）

    ID      time            temperature

133312  2013-04-06 03:29:36 25.37
133313  2013-04-06 03:30:36 25.37
133314  2013-04-06 03:31:36 25.37
133315  2013-04-06 03:32:36 25.31
133316  2013-04-06 03:33:36 25.31
133317  2013-04-06 03:34:36 25.31
133318  2013-04-06 03:35:36 25.37
133319  2013-04-06 03:36:36 25.31
133320  2013-04-06 03:37:36 25.31
133321  2013-04-06 03:38:36 25.31
133322  2013-04-06 03:39:36 25.37

表格实体（仅提取，此表格非常大，包含超过 130,000 个值）

    ID      time            solids

123791  2013-04-06 03:29:49 140
123792  2013-04-06 03:30:49 140
123793  2013-04-06 03:31:49 143
123794  2013-04-06 03:32:49 140
123795  2013-04-06 03:33:49 140
123796  2013-04-06 03:34:49 140
123797  2013-04-06 03:35:49 140
123798  2013-04-06 03:36:49 143
123799  2013-04-06 03:37:49 140
123800  2013-04-06 03:38:49 140
123801  2013-04-06 03:39:49 140

我目前正在使用下面的查询获取每小时平均值

SELECT DATE_FORMAT(x.time,'%Y-%m-%d %H:00:00')
     , avg(x.solids) avg_solids
  FROM solids x where time >= NOW() - INTERVAL 1 DAY
 GROUP 
    BY DATE_FORMAT(x.time,'%Y-%m-%d %H:00:00'); 

如何有效地加入（相对于时间）上面查询的结果，每个传感器 (x3) 显示在 1 个表中

=================================

下面的这个查询获取每小时的值，但不确定如何调整它以获得每小时的平均值

SELECT DATE_FORMAT(timeTable.minuteTime, '%Y-%m-%d %k:%i') time,
(oT2.temperature) temperature,
(T2.temperature) temp,
(S2.solids) solids,
(P2.Ph) Ph


FROM
(
    SELECT minuteTime.minuteTime minuteTime,
    ( SELECT MAX(time) FROM outside_temperature WHERE time <= minuteTime.minuteTime AND time >= NOW() - INTERVAL 1 DAY) otempTime, 
    ( SELECT MAX(time) FROM temperature1 WHERE time <= minuteTime.minuteTime AND time >= NOW() - INTERVAL 1 DAY) tempTime, 
    ( SELECT MAX(time) FROM Ph WHERE time <= minuteTime.minuteTime AND time >= NOW() - INTERVAL 1 DAY) phTime,  
    ( SELECT MAX(time) FROM solids WHERE time <= minuteTime.minuteTime AND time >= NOW() - INTERVAL 1 DAY) solidsTime

    FROM  
    (
        SELECT DATE(time) + INTERVAL (HOUR(time) DIV 1 *1 ) HOUR minuteTime
        FROM Ph
        WHERE time >= NOW() - INTERVAL 1 DAY AND time <= NOW()
        UNION SELECT DATE(time) + INTERVAL (HOUR(time) DIV 1 *1) HOUR
        FROM solids
        WHERE time >= NOW() - INTERVAL 1 DAY AND time <= NOW()
        UNION SELECT DATE(time) + INTERVAL (HOUR(time) DIV 1 *1) HOUR
        FROM outside_temperature
        WHERE time >= NOW() - INTERVAL 1 DAY AND time <= NOW()
        UNION SELECT DATE(time) + INTERVAL (HOUR(time) DIV 1 *1) HOUR
        FROM temperature1
        WHERE time >= NOW() - INTERVAL 1 DAY AND time <= NOW()
        GROUP BY 1
    ) minuteTime
) timeTable
LEFT JOIN outside_temperature oT2 ON oT2.time = timeTable.otempTime
LEFT JOIN temperature1 T2 ON T2.time = timeTable.tempTime
LEFT JOIN solids S2 ON S2.time = timeTable.solidsTime
LEFT JOIN Ph P2 ON P2.time = timeTable.phTime


GROUP BY DATE_FORMAT(timeTable.minuteTime, '%Y-%m-%d %k:%i') 
ORDER BY minuteTime ASC

Answer 1

Hour() 似乎对此很有用，因为您只查看一天。也许这样的事情对你有用：

SELECT * FROM
 (SELECT HOUR(time) hour, avg(ph) AS avg_ph
  FROM ph 
  WHERE time >= NOW() - INTERVAL 1 DAY
  GROUP BY hour) p
JOIN 
 (SELECT HOUR(time) hour, avg(temperature) AS avg_temp
  FROM temperature1 
  WHERE time >= NOW() - INTERVAL 1 DAY
  GROUP BY hour) t ON t.hour = p.hour
JOIN 
 (SELECT HOUR(time) hour, avg(solids) AS avg_solids
  FROM solids 
  WHERE time >= NOW() - INTERVAL 1 DAY
  GROUP BY hour) s ON s.hour = p.hour;

由于它使用的是内部连接，我假设每个表一小时内总是至少有一条记录，但这似乎是一个合理的假设。