Mysql的JOIN基於異步時間和平均值

我記錄從溫度和溼度傳感器的值，這樣的兩個表：從this post我用這個MySQL的命令來連接兩個表，並得到一個值Mysql的JOIN基於異步時間和平均值

mysql> SELECT date,valeur FROM temperature WHERE date >= NOW() - INTERVAL 2 HOUR; 
+---------------------+--------+ 
| date    | valeur | 
+---------------------+--------+ 
| 2013-09-26 11:30:40 | 25.2 | 
| 2013-09-26 11:33:19 | 25.4 | 
| 2013-09-26 11:34:12 | 25.5 | 
| 2013-09-26 11:38:37 | 25.4 | 
| 2013-09-26 11:39:30 | 25.4 | 
| 2013-09-26 11:40:23 | 25.4 | 
| 2013-09-26 11:43:02 | 25.4 | 
| 2013-09-26 11:45:41 | 25.3 | 
| 2013-09-26 11:47:33 | 25.3 | 
| 2013-09-26 11:51:07 | 25.4 | 
| 2013-09-26 11:51:52 | 25.3 | 
| 2013-09-26 11:53:38 | 25.4 | 
... 
| 2013-09-26 12:26:20 | 25.5 | 
| 2013-09-26 12:27:12 | 25.5 | 
| 2013-09-26 12:32:30 | 25.4 | 
| 2013-09-26 12:35:09 | 25.5 | 
| 2013-09-26 12:36:02 | 25.5 | 
| 2013-09-26 12:37:50 | 25.6 | 
| 2013-09-26 12:40:27 | 25.6 | 
| 2013-09-26 12:49:18 | 25.6 | 
| 2013-09-26 12:52:54 | 25.6 | 
... 
| 2013-09-26 13:16:40 | 25.5 | 
| 2013-09-26 13:17:33 | 25.6 | 
| 2013-09-26 13:22:05 | 25.5 | 
| 2013-09-26 13:22:51 | 25.5 | 
| 2013-09-26 13:23:44 | 25.5 | 
| 2013-09-26 13:24:37 | 25.5 | 
| 2013-09-26 13:25:30 | 25.5 | 
| 2013-09-26 13:28:09 | 25.6 | 
+---------------------+--------+ 

mysql> SELECT date,valeur FROM humidite WHERE date >= NOW() - INTERVAL 2 HOUR; 
+---------------------+--------+ 
| date    | valeur | 
+---------------------+--------+ 
| 2013-09-26 11:30:40 |  78 | 
| 2013-09-26 11:33:19 |  78 | 
| 2013-09-26 11:34:12 |  78 | 
| 2013-09-26 11:38:37 |  78 | 
| 2013-09-26 11:39:30 |  78 | 
| 2013-09-26 11:40:23 |  78 | 
| 2013-09-26 11:43:02 |  79 | 
| 2013-09-26 11:45:41 |  78 | 
| 2013-09-26 11:47:33 |  78 | 
| 2013-09-26 11:51:07 |  79 | 
| 2013-09-26 11:51:52 |  79 | 
| 2013-09-26 11:53:38 |  79 | 
... 
| 2013-09-26 12:22:48 |  78 | 
| 2013-09-26 12:26:20 |  78 | 
| 2013-09-26 12:27:12 |  78 | 
| 2013-09-26 12:32:30 |  77 | 
| 2013-09-26 12:35:09 |  77 | 
| 2013-09-26 12:36:02 |  77 | 
| 2013-09-26 12:37:50 |  78 | 
| 2013-09-26 12:40:27 |  77 | 
| 2013-09-26 12:43:06 |  78 | 
| 2013-09-26 13:22:05 |  78 | 
... 
| 2013-09-26 13:22:51 |  78 | 
| 2013-09-26 13:23:44 |  78 | 
| 2013-09-26 13:24:37 |  78 | 
| 2013-09-26 13:25:30 |  78 | 
| 2013-09-26 13:28:09 |  78 | 
+---------------------+--------+

因爲每24小時小時：

SELECT DATE_FORMAT(timeTable.minuteTime, '%Y-%m-%d %k:%i') date, 
T2.valeur temp, 
P2.valeur hum 
FROM 
(
    SELECT minuteTime.minuteTime minuteTime, 
    (SELECT MAX(date) FROM temperature WHERE date <= minuteTime.minuteTime AND date >= NOW() - INTERVAL 1 DAY) tempTime, 
    (SELECT MAX(date) FROM humidite WHERE date <= minuteTime.minuteTime AND date >= NOW() - INTERVAL 1 DAY) humTime 
    FROM 
    (
     SELECT DATE(date) + INTERVAL (HOUR(date) DIV 1 * 1) HOUR minuteTime 
     FROM humidite 
     WHERE date >= NOW() - INTERVAL 1 DAY AND date <= NOW() 
     UNION SELECT DATE(date) + INTERVAL (HOUR(date) DIV 1 * 1) HOUR 
     FROM temperature 
     WHERE date >= NOW() - INTERVAL 1 DAY AND date <= NOW() 
     GROUP BY 1 
    ) minuteTime 
) timeTable 
LEFT JOIN temperature T2 ON T2.date = timeTable.tempTime 
LEFT JOIN humidite P2 ON P2.date = timeTable.humTime 
ORDER BY minuteTime ASC;

它運作良好，但我真的不知道該值是如何選擇（隨機在區間？）。我寧願平均每個小時，而不是：

+------------------+------+------+ 
| date    | temp | hum | 
+------------------+------+------+ 
| 2013-09-25 13:00 | NULL | NULL | 
| 2013-09-25 14:00 | 25.1 | 80 | 
| 2013-09-25 15:00 | 25.3 | 78 | 
| 2013-09-25 16:00 | 25.6 | 75 | 
| 2013-09-25 17:00 | 25.5 | 75 | 
| 2013-09-25 18:00 | 25.0 | 78 | 
| 2013-09-25 19:00 | 24.2 | 80 | 
| 2013-09-25 20:00 | 23.9 | 84 | 
| 2013-09-25 21:00 | 23.9 | 84 | 
| 2013-09-25 22:00 | 24.1 | 83 | 
| 2013-09-25 23:00 | 24.1 | 83 | 
| 2013-09-26 0:00 | 24.0 | 82 | 
| 2013-09-26 1:00 | 23.9 | 84 | 
| 2013-09-26 2:00 | 23.7 | 86 | 
| 2013-09-26 3:00 | 23.7 | 84 | 
| 2013-09-26 4:00 | 23.7 | 85 | 
| 2013-09-26 5:00 | 23.4 | 85 | 
| 2013-09-26 6:00 | 23.6 | 85 | 
| 2013-09-26 7:00 | 23.7 | 85 | 
| 2013-09-26 8:00 | 24.0 | 84 | 
| 2013-09-26 9:00 | 24.4 | 82 | 
| 2013-09-26 10:00 | 24.6 | 81 | 
| 2013-09-26 11:00 | 25.2 | 79 | 
| 2013-09-26 12:00 | 25.4 | 79 | 
| 2013-09-26 13:00 | 25.6 | 78 | 
+------------------+------+------+ 
25 rows in set (1.11 sec)

你知道如何把AVG（）在此代碼？

獎金問題：我改變了代碼，以獲得每小時一個值。你知道如何每30分鐘獲得一個值嗎？

感謝您的幫助

來源

2013-09-26 iero

試試這個：

select FROM_UNIXTIME(TRUNCATE(UNIX_TIMESTAMP(timeTable.minuteTime)/1800,0)*1800) as halfHour, 
avg(T2.valeur) as avgTemp, 
avg(P2.valeur) as avgHum 
FROM 
(
    SELECT minuteTime.minuteTime minuteTime, 
    (SELECT MAX(date) FROM temperature WHERE date <= minuteTime.minuteTime AND date >= NOW() - INTERVAL 1 DAY) tempTime, 
    (SELECT MAX(date) FROM humidite WHERE date <= minuteTime.minuteTime AND date >= NOW() - INTERVAL 1 DAY) humTime 
    FROM 
    (
     SELECT DATE(date) + INTERVAL (HOUR(date) DIV 1 * 1) HOUR minuteTime 
     FROM humidite 
     WHERE date >= NOW() - INTERVAL 1 DAY AND date <= NOW() 
     UNION SELECT DATE(date) + INTERVAL (HOUR(date) DIV 1 * 1) HOUR 
     FROM temperature 
     WHERE date >= NOW() - INTERVAL 1 DAY AND date <= NOW() 
     GROUP BY 1 
    ) minuteTime 
) timeTable 
LEFT JOIN temperature T2 ON T2.date = timeTable.tempTime 
LEFT JOIN humidite P2 ON P2.date = timeTable.humTime 
group by FROM_UNIXTIME(TRUNCATE(UNIX_TIMESTAMP(timeTable.minuteTime)/1800,0)*1800) 
ORDER BY 1 ASC;

來源

2013-09-26 13:23:20

感謝湯姆的Mac您的回覆。平均值似乎表現良好，但產出仍然是一小時一小時，而不是每30分鐘一次。也許我需要改變日期（日期）+ INTERVAL HOUR（日期）HOUR分鐘時間由別的東西？ – iero

我再次測試，平均值給出了奇怪的值：溫度始終爲ab.c0000，溼度始終爲de.0。它似乎太「圓潤」成爲一個真正的平均值！一個主意？ – iero

感謝湯姆Mac和其他有用的帖子在這個網站，我結束了這段代碼：

select DATE_FORMAT(timeTable.minuteTime, '%Y-%m-%d %k:%i') as date, 
    (UNIX_TIMESTAMP(timeTable.minuteTime)*1000) AS dte, 
    T2.valeur as avgTemp, 
    P2.valeur as avgHum 
    FROM ( 
    SELECT minuteTime.minuteTime minuteTime,  
    (SELECT MAX(date) FROM temperature WHERE date <= minuteTime.minuteTime AND 
    date >= NOW() - INTERVAL 170 HOUR) tempTime, 
    (SELECT MAX(date) FROM humidite WHERE date <= minuteTime.minuteTime AND 
    date >= NOW() - INTERVAL 170 HOUR) humTime 
    FROM( 
    SELECT date + INTERVAL 59 - SECOND(date) SECOND minuteTime 
    FROM humidite 
    WHERE date >= NOW() - INTERVAL 7 DAY AND date <= NOW() 
    UNION SELECT date + INTERVAL 59 - SECOND(date) SECOND 
    FROM temperature 
    WHERE date >= NOW() - INTERVAL 7 DAY AND date <= NOW() 
    GROUP BY 1 
    ) minuteTime 
) timeTable 
    LEFT JOIN temperature T2 ON T2.date = timeTable.tempTime 
    LEFT JOIN humidite P2 ON P2.date = timeTable.humTime 
    group by FROM_UNIXTIME(TRUNCATE(UNIX_TIMESTAMP(timeTable.minuteTime)/1800,0)*1800) 
    ORDER BY minuteTime ASC;

現在我能夠使用我在此處提供的專用php代碼來計算每小時的露點：（012信息）：

function calculateDewPoint($temperature, $humidity) { 
    $a = 17.27 ; 
    $b = 237.7 ; 

    $c = (($a * $temperature)/($b + $temperature)) + Log($humidity/100) ; 
    $d = (($b * $c)/($a - $c)); 
    return number_format($d, 1); 
}

下次更新將直接把這個代碼在MySQL的要求..

問候

來源

2013-10-10 07:55:14 iero

Mysql的JOIN基於異步時間和平均值

回答

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