从一个带有时间戳的表中获取最大值，并在一段时间内从另一张表中获取3秒

Question

当EndTime表值为TimeStr时，我需要显示带有hopper2_setpoint_met值的1，并且需要将Weight显示为当设定点满足表的值为MAX(Value)时，hopper2_liveweight的{​​{1}}表中的TimeStr +3 second从TimeStr值开始。

所需结果示例

1

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数据和我的尝试

您可以从此SQLFiddle帖子中访问此数据，在该帖子中我构建了架构并插入了数据的一小部分，或者如果您想使用它在自己的MySQL数据库表上创建，那么这里是该SQL的也是

+---------------------+--------+
|       EndTime       | Weight | 
+---------------------+--------+
| 2019-06-30 12:02:33 |   300  |
| 2019-06-30 12:04:45 |   299  | 
+---------------------+--------+

---

我昨天在MySQL to select max value between on and off time stamps plus 3 seconds上发布了关于运输商的类似信息，但我了解到使用temp表并不是最佳解决方案，尽管在那里收到的答案确实给了我所要求的预期结果。 / p>

我还从收到的这些答案中学到了一些东西，并尝试了这些事情的几种变体，例如CREATE TABLE `hopper2_setpoint_met` ( `TimeStr` datetime NOT NULL, `Value` int(11) NOT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8; INSERT INTO `hopper2_setpoint_met` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:02:33',1); INSERT INTO `hopper2_setpoint_met` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:03:51',0); INSERT INTO `hopper2_setpoint_met` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:45',1); INSERT INTO `hopper2_setpoint_met` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:05:56',0); INSERT INTO `hopper2_setpoint_met` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:49',1); CREATE TABLE `hopper2_liveweight` ( `TimeStr` datetime NOT NULL, `Value` int(11) NOT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8; INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:02:33',292); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:02:34',298); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:02:35',300); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:02:36',300); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:14',106); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:15',111); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:16',116); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:17',123); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:19',132); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:20',142); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:21',148); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:22',154); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:23',160); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:24',166); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:25',172); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:26',177); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:27',184); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:29',190); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:30',195); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:31',201); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:32',208); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:33',213); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:34',220); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:35',226); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:36',232); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:37',239); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:38',244); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:39',251); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:40',257); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:41',263); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:42',269); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:43',276); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:44',282); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:45',288); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:46',293); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:47',299); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:04:48',299); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:18',108); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:19',112); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:20',117); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:21',123); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:22',128); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:23',135); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:24',141); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:25',148); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:26',154); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:27',160); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:28',165); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:29',172); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:30',177); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:31',183); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:32',190); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:33',196); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:34',201); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:35',208); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:36',213); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:37',220); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:38',226); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:39',231); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:40',237); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:41',242); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:42',248); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:43',254); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:44',262); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:45',269); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:46',276); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:47',282); INSERT INTO `hopper2_liveweight` (`TimeStr`,`Value`) VALUES ('2019-06-30 12:06:49',288); 技巧和其他一些新任务，而我又难以获得预期的结果结果。

如果我将数据放入临时表中，我当然可以得到预期的结果，但是它不能很好地执行，并且我认为它也使过程变得复杂，并且并不是真正需要的。

我使用If(CAST(Value AS UNSIGNED) != 0, Value, Null) Weight语句和JOIN数据以及子查询尝试了几种不同的变体，当我尝试获得timestr + 3秒记录之间的最大权重时，我的表现不足。 >

我很想学习新的知识，并且从有助于解决该问题的答案中想到一个灯泡，所以继续前进，这是应用类似逻辑而不需要创建临时或永久临时表的问题。 / p>

将所有内容保留在带有一些UNION语句的查询中，或者如果需要的话甚至可以包含多个子查询，这对我来说也可以。我不确定使用MySQL会话变量是否会有所帮助，但是我什至尝试了一些尝试并失败了。

Answer 1

一个合适的查询是：

SELECT sm.TimeStr AS EndTime, Max(lw.Value) AS Weight
FROM (SELECT TimeStr FROM hopper2_setpoint_met WHERE Value = 1) sm
INNER JOIN hopper2_liveweight lw ON (sm.TimeStr + INTERVAL 3 SECOND) = lw.TimeStr
GROUP BY sm.TimeStr
;