MYSQL平均日期时间

Question

我有下面的SQL语句并正确生成相关输出（I希望将每3个分钟值）：

SELECT date_time date, UNIX_TIMESTAMP(date_time) AS time_value, 
FLOOR((MINUTE(date_time) + (HOUR(date_time)*60))/3) AS minute_value, ph1_active_power AS p1 
FROM powerpro1 
GROUP BY date_time 

生成的输出：

+-----------+---------------------+------------+--------------+---------+ 
| record_no |  date   | time_value | minute_value | p1 | 
+-----------+---------------------+------------+--------------+---------+ 
|   1 | 2014-12-01 00:00:00 | 1417372200 |   0 | 73.0767 | 
|   2 | 2014-12-01 00:01:00 | 1417372260 |   0 | 73.0293 | 
|   3 | 2014-12-01 00:02:00 | 1417372320 |   0 | 72.9818 | 
|   4 | 2014-12-01 00:03:00 | 1417372380 |   1 | 72.9343 | 
|   5 | 2014-12-01 00:04:00 | 1417372440 |   1 | 72.8868 | 
|   6 | 2014-12-01 00:05:00 | 1417372500 |   1 | 72.8392 | 
|   7 | 2014-12-01 00:06:00 | 1417372560 |   2 | 72.7916 | 
|   8 | 2014-12-01 00:07:00 | 1417372620 |   2 | 72.744 | 
|   9 | 2014-12-01 00:08:00 | 1417372680 |   2 | 72.6963 | 
|  10 | 2014-12-01 00:09:00 | 1417372740 |   3 | 72.6486 | 
|  11 | 2014-12-01 00:10:00 | 1417372800 |   3 | 72.6009 | 
|  12 | 2014-12-01 00:11:00 | 1417372860 |   3 | 72.5531 | 
|  13 | 2014-12-01 00:12:00 | 1417372920 |   4 | 72.5053 | 
|  14 | 2014-12-01 00:13:00 | 1417372980 |   4 | 72.4575 | 
|  15 | 2014-12-01 00:14:00 | 1417373040 |   4 | 72.4096 | 
|  16 | 2014-12-01 00:15:00 | 1417373100 |   5 | 72.3617 | 
|  17 | 2014-12-01 00:16:00 | 1417373160 |   5 | 72.3137 | 
|  18 | 2014-12-01 00:17:00 | 1417373220 |   5 | 72.2657 | 
|  19 | 2014-12-01 00:18:00 | 1417373280 |   6 | 72.2177 | 
|  20 | 2014-12-01 00:19:00 | 1417373340 |   6 | 72.1697 | 
|  21 | 2014-12-01 00:20:00 | 1417373400 |   6 | 72.1216 | 
|  22 | 2014-12-01 00:21:00 | 1417373460 |   7 | 72.0734 | 
|  23 | 2014-12-01 00:22:00 | 1417373520 |   7 | 72.0253 | 
|  24 | 2014-12-01 00:23:00 | 1417373580 |   7 | 71.9771 | 
+-----------+---------------------+------------+--------------+---------+ 

但是，我想要获得时间值的平均值和p1的平均值，然后需要按minute_值GROUP。如果我使用上面的查询以及相关更改如下，

SELECT date_time date, AVG(UNIX_TIMESTAMP(date_time)) AS time_value, FLOOR((MINUTE(date_time) + (HOUR(date_time)*60))/3) AS minute_value, ROUND(AVG(ph1_active_power),4) AS p1 
FROM powerpro1 
GROUP BY minute_value 

我得到了不正确的输出，如下所述。

+-----------+---------------------+-----------------+--------------+--------+ 
| record_no |  date   | time_value | minute_value | p1 | 
+-----------+---------------------+-----------------+--------------+--------+ 
|   1 | 2014-12-01 00:00:00 | 1418754688.6364 |   0 | 2.2622 | 
|   4 | 2014-12-01 00:03:00 | 1418754868.6364 |   1 | 2.2541 | 
|   7 | 2014-12-01 00:06:00 | 1418755048.6364 |   2 | 2.246 | 
|  10 | 2014-12-01 00:09:00 | 1418755228.6364 |   3 | 2.2378 | 
|  13 | 2014-12-01 00:12:00 | 1418755408.6364 |   4 | 2.2297 | 
|  16 | 2014-12-01 00:15:00 | 1418755588.6364 |   5 | 2.2216 | 
|  19 | 2014-12-01 00:18:00 | 1418755768.6364 |   6 | 2.2134 | 
|  22 | 2014-12-01 00:21:00 | 1418755948.6364 |   7 | 2.2052 | 
+-----------+---------------------+-----------------+--------------+--------+ 

所需的输出：

+-----------+---------------------+--------------+------------+---------+ 
| record_no |  time_value  | minute_value | time_value | p1 | 
+-----------+---------------------+--------------+------------+---------+ 
|   2 | 2014-12-01 00:01:00 |   0 | 1417372260 | 73.0293 | 
|   5 | 2014-12-01 00:04:00 |   1 | 1417372440 | 72.8868 | 
|   8 | 2014-12-01 00:07:00 |   2 | 1417372620 | 72.744 | 
|  11 | 2014-12-01 00:10:00 |   3 | 1417372800 | 72.6009 | 
|  14 | 2014-12-01 00:13:00 |   4 | 1417372980 | 72.4575 | 
+-----------+---------------------+--------------+------------+---------+ 

什么可能是错误的。

任何人都可以帮助我使用宝贵的时间和知识。

Answer 1

你可以试试吗？

SELECT date_time date, SUM(UNIX_TIMESTAMP(date_time))/COUNT(record_no) AS time_value, FLOOR((MINUTE(date_time) + (HOUR(date_time)*60))/3)*3 AS minute_value, ROUND((SUM(ph1_active_power)/COUNT(record_no)),4) AS p1 
FROM powerpro1 
GROUP BY minute_value 

我已经通过下面的查询做了：

SELECT record_no, date_time, 
ROUND(AVG(UNIX_TIMESTAMP(date_time))) AS time_value, 
ROUND(AVG(ph1_active_power),4) AS p1 
FROM powerpro1 
WHERE date_time <= '2014-12-20 00:00:00' 
GROUP BY date_time DIV 300