MySQL 分组依据与时间差异

Question

我的表记录如下:

id         startFrom                   endOn               gateway   broadcast
1    2018-09-01T23:41:24:024  2018-09-01T23:45:24:028         A         X01
2    2018-09-01T23:41:24:025  2018-09-01T23:45:24:032         A         X01
3    2018-09-01T23:41:24:026  2018-09-01T23:45:24:028         B         X01
4    2018-09-01T23:41:24:030  2018-09-01T23:45:24:045         C         X01
5    2018-09-01T22:41:24:029  2018-09-01T23:41:24:784         B         X02
6    2018-09-01T23:41:24:025  2018-09-01T23:45:24:038         A         X01

如果我想使用单个查询来查找特定广播中每个网关中的第一个请求时间段。如何使用MySQL对其进行分组查询？

失败:

SELECT gateway, TIMESTAMPDIFF(MICROSECOND, `startFrom`, `endOn`) AS `timeDiff` FROM Records WHERE broadcast = 'X01' GROUP BY gateway

如果我尝试制作一个临时表，例如:

SELECT gateway, MIN(timeDiff)
FROM (SELECT TIMESTAMPDIFF(MICROSECOND, `startFrom`, `endOn`) AS `timeDiff`, gateway, broadcast FROM Records) t
WHERE broadcast = 'X01'
GROUP BY gateway;

它只能从该广播中每个网关的记录中获取最小时间差异，但我必须查询“第一条记录”(=> ORDER BY startFrom ASC)时间差异。

目标输出是:

gateway        startFrom                 endOn                 timeDiff
A       2018-09-01T23:41:24:024  2018-09-01T23:45:24:028         4000  
B       2018-09-01T23:41:24:026  2018-09-01T23:45:24:028         2000  
C       2018-09-01T23:41:24:030  2018-09-01T23:45:24:045         15000  

感谢您的阅读和帮助

Answer 1

从记录中选择*；
+----+---------------------+---------------------+ --------+------------+
|编号 |开始于 |结束 |网关|广播|
+----+---------------------+---------------------+ --------+------------+
| 1 | 2018-09-17 05:23:53 | 2018-09-17 06:23:53 |一个 | X01 |
| 2 | 2018-09-17 05:24:08 | 2018-09-17 06:24:08 |一个 | X01 |
| 3 | 2018-09-17 05:24:25 | 2018-09-17 06:24:25 |乙| X01 |
| 4 | 2018-09-17 05:24:32 | 2018-09-17 06:24:32 | C | X01 |
| 5 | 2018-09-17 05:24:42 | 2018-09-17 07:24:42 |乙| X02 |
+----+---------------------+---------------------+ ---------+------------+

这是您正在寻找的查询吗..

从网关 asc 的记录组中选择 gateway,startFrom,endOn,time_to_sec(timediff(endOn,startFrom)) 作为 timeDiff ；
+---------+--------------------+----------------- ----+----------+
|网关|开始于 |结束 |时间差 |
+---------+--------------------+----------------- ----+----------+
|一个 | 2018-09-17 05:23:53 | 2018-09-17 06:23:53 | 3600 |
|乙| 2018-09-17 05:24:25 | 2018-09-17 06:24:25 | 3600 |
| C | 2018-09-17 05:24:32 | 2018-09-17 06:24:32 | 3600 |
+---------+--------------------+----------------- ---+----------+