Question

我有一个带有时间戳（DATETIME）值的表。

表MyLog：

+----------+---------------------+--------+
+
| logNo    | timestamp           | temp   |
|
+----------+---------------------+--------+
+
|        1 | 2016-04-24 15:57:56 |   29.6 |
|
|        2 | 2016-04-24 16:59:24 |   29.7 |
|
|        3 | 2016-04-24 18:01:52 |   29.6 |
|
|        4 | 2016-04-24 18:59:20 |   29.6 |
+----------+---------------------+--------+

我有另一张桌子（HourLog）可以拉出“临时表”。来自＆＃39; MyLog＆＃39;的价值每个小时的最高点（HH：00：00），其值为＆＃39;时间戳＆＃39;最接近＆＃39;时间戳＆＃39; HourLog中的值（因为时间戳值不能总是正好是HH：00：00）。

HourLog：

+----------+---------------------+--------+
+
|logNo      | timestamp          | temp   |
|
+----------+---------------------+--------+
+
|        1 | 2016-04-24 00:00:00 |   29.6 |
|
|        2 | 2016-04-24 01:00:00 |   29.7 |
|
|        3 | 2016-04-24 02:00:00 |   29.6 |
|
|        4 | 2016-04-24 03:00:00 |   29.6 |
|
|        5 | 2016-04-24 04:00:00 |   29.7 |
|
|        6 | 2016-04-24 05:00:00 |   29.8 |
|
|        7 | 2016-04-24 06:00:00 |   30.2 |
|
|        8 | 2016-04-24 07:00:00 |   30.1 |
|
|        9 | 2016-04-24 08:00:00 |   30.1 |
|
|       10 | 2016-04-24 09:00:00 |   30.1 |
|
|       11 | 2016-04-24 10:00:00 |   30.0 |
|
|       12 | 2016-04-24 11:00:00 |   30.1 |
|
|       13 | 2016-04-24 12:00:00 |   30.1 |
|
|       14 | 2016-04-24 13:00:00 |   29.9 |
|
|       15 | 2016-04-24 14:00:00 |   29.8 |
|
|       16 | 2016-04-24 15:00:00 |   29.6 |
|
|       17 | 2016-04-24 16:00:00 |   29.6 |
|
|       18 | 2016-04-24 17:00:00 |   29.7 |
|
|       19 | 2016-04-24 18:00:00 |   29.6 |
|
|       20 | 2016-04-24 19:00:00 |   29.6 |
+----------+---------------------+--------+

我想写的查询应该能够查看MyLog中的时间戳值，获取最接近当前小时的值并插入＆＃39; temp＆＃39;使用（HH：00：00）时间戳记将值写入HourLog。

一个例子： MyLog

+----------+---------------------+--------+
+
| logNo    | timestamp           | temp   |
|
+----------+---------------------+--------+
+
|      101 | 2016-04-24 17:57:56 |   29.6 |
|
|      102 | 2016-04-24 17:59:24 |   29.7 |
|
|      103 | 2016-04-24 18:01:52 |   29.6 |
|
|      104 | 2016-04-24 18:04:20 |   29.6 |
+----------+---------------------+--------+

查询选择logNo 102，因为它的时间戳值最接近小时的最高点（18:00:00），并插入＆＃39; temp＆＃39;值为HourLog logNo 74

HourLog：

+----------+---------------------+--------+
+
| logNo    | timestamp           | temp   |
|
+----------+---------------------+--------+
+
|       71 | 2016-04-24 15:00:00 |   28.6 |
|
|       72 | 2016-04-24 16:00:00 |   28.7 |
|
|       73 | 2016-04-24 17:00:00 |   30.1 |
|
|       74 | 2016-04-24 18:00:00 |   29.6 |
+----------+---------------------+--------+

如何在MySQL中编写这样的预定查询？

Answer 1

忍受我，但尝试创建一个像这样的SQL文件，称之为query.sql：

SET @n = NOW();

INSERT INTO HourLog

SELECT 0, @n, X.temp (
    SELECT 
        TIMESTAMPDIFF(SECOND, timestamp, @n) diff, 
        temp
    FROM MyLog
    ORDER BY diff ASC
    LIMIT 1
) X;

然后创建一个调用该文件（script.sh）的shell脚本：

mysql --login-path=[your login path] [your database] < /path/to/query.sql

然后你应该能够像这样调用一个cron工作：

0 * * * * /path/to/script.sh

如何制作计划的MySql查询，以便每小时都能选择数据？

1 个答案: