blocks|key|525226|text|使用聚合来获取最大时间，然后使用连接来获取与该时间匹配的其余记录：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|525227|SELECT+e.sensor_id,+e.event_type,+e.value,+e.time
from+events+e+join
+++++(select+sensor_id,+event_type,+max(time)+as+maxt
++++++from+events+e
++++++group+by+sensor_id,+event_type
+++++)+ee
+++++on+e.sensor_id+=+ee.sensor_id+and+e.event_type+=+ee.event_type;|code-block|syntax|javascript|525228|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Use aggregation to get the maximum time, and then a join to get the rest of the record that match that time:

<pre><code>SELECT e.sensor_id, e.event_type, e.value, e.time
from events e join
 (select sensor_id, event_type, max(time) as maxt
 from events e
 group by sensor_id, event_type
 ) ee
 on e.sensor_id = ee.sensor_id and e.event_type = ee.event_type;
</code></pre>

blocks|key|856793|text|也可以试试下面的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|856794|选择sensor_id、event_type、value、time|856795|从事件|856796|where+time+in+(从按sensor_id、event_type分组的事件组中选择最大(时间))|856797|希望这也能很好地工作。|856798|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|N|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|O|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|P|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|K|$]]

Try with the below one also.

select sensor_id,event_type,value, time

from events

where time in (select max(time) from events group by sensor_id, event_type)

Hope this will also work fine.

blocks|key|4307786|text|通过这种方式，它可以正常工作|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4307787|--+write+your+code+in+PostgreSQL+9.4
SELECT
++++E1.SENSOR_ID,
++++COUNT(E1.EVENT_TYPE)+AS+"TYPES"
FROM
++++(
++++++++SELECT+
++++++++++++DISTINCT
++++++++++++E.SENSOR_ID,
++++++++++++E.EVENT_TYPE
++++++++FROM
++++++++++++EVENTS+E
++++)+E1
GROUP+BY+E1.SENSOR_ID
ORDER+BY+E1.SENSOR_ID+ASC|code-block|syntax|javascript|4307788|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

In this way it works properly

<pre><code>-- write your code in PostgreSQL 9.4
SELECT
 E1.SENSOR_ID,
 COUNT(E1.EVENT_TYPE) AS "TYPES"
FROM
 (
 SELECT 
 DISTINCT
 E.SENSOR_ID,
 E.EVENT_TYPE
 FROM
 EVENTS E
 ) E1
GROUP BY E1.SENSOR_ID
ORDER BY E1.SENSOR_ID ASC
</code></pre>

blocks|key|856817|text|SELECT+sensor_id，event_type，value+from+(SELECT+sensor_id，event_type，value，max(time)+from+events+group+by+sensor_id，event_type)+order+by+sensor_id，event_type；|type|unstyled|depth|inlineStyleRanges|entityRanges|data|856818|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

SELECT sensor_id, event_type, value
from (SELECT sensor_id, event_type, value, max(time)
from events group by sensor_id, event_type)
order by sensor_id, event_type;

blocks|key|525332|text|SELECT+events.sensor_id,+events.event_type,+events.value
FROM+events
JOIN+(
++++SELECT+sensor_id,+event_type,+MAX(time)+as+max_time
++++FROM+events
++++GROUP+BY+sensor_id,+event_type
)t+on+events.sensor_id+=+t.sensor_id+and+events.event_type+=+t.event_type+and+events.time+=+t.max_time
ORDER+BY+events.sensor_id,+events.event_type;|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|525333|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>SELECT events.sensor_id, events.event_type, events.value
FROM events
JOIN (
 SELECT sensor_id, event_type, MAX(time) as max_time
 FROM events
 GROUP BY sensor_id, event_type
)t on events.sensor_id = t.sensor_id and events.event_type = t.event_type and events.time = t.max_time
ORDER BY events.sensor_id, events.event_type;
</code></pre>

I have table

<pre><code>create table events (
 sensor_id integer not null,
 event_type integer not null,
 value integer not null,
 time timestamp unique not null);

insert into events
values
(2,2,5,"2014-02-13 12:42:00"),
(2,4,-42,"2014-02-13 13:19:57"),
(2,2,2,"2014-02-13 14:48:30"),
(3,2,7,"2014-02-13 12:54:39"),
(2,3,54,"2014-02-13 13:32:36");
</code></pre>

I want for each sensor_id and event_type only the most recent value in terms of time 

expected result

<pre><code>sensor_id, event_type value
2 2 2
2 3 54
2 4 -42
3 2 7
</code></pre>

I have tried query

<pre><code>SELECT sensor_id,event_type,value, time
from events
group by sensor_id,event_type
having time = max(time)
</code></pre>

why it doesn't success (result table do not contain sensor_id = 2 and event_type = 2)

How could I solve this using both mysql and sqllite, is there difference in term of this ?

How to select the value from recent record?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

我有桌子create table events (  sensor_id integer not null,  event_type integer not null,  value integer not null,  time timestamp unique not null);insert into event...

问如何从最近的记录中选择数值？
EN

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问如何从最近的记录中选择数值？EN