blocks|key|2152864|text|最简单的方法是使用ANSI标准的窗口函数(特别是row_number())。但MySQL+(目前)还不支持这些。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2152865|在MySQL中，最好的方法可能是使用变量：|2152866|SELECT+.+.+.
FROM+tbl_device+d+JOIN
+++++(SELECT+t.*,
+++++++++++++(@rn+:=+if(@d+=+t.devid,+@rn+%2B+1,
++++++++++++++++++++++++if(@d+:=+t.devid,+1,+1)
+++++++++++++++++++++++)
+++++++++++++)+as+rn
++++++FROM+(SELECT+t.*
++++++++++++FROM+tbl_temperature+t
++++++++++++ORDER+BY+DevID,+id+DESC
+++++++++++)+t+CROSS+JOIN
+++++++++++(SELECT+@d+:=+-1,+@rn+:=+0)+params
+++++)+t
+++++ON+tbl_device.ID+=+tbl_temperature.DevID
WHERE+rn+<=+3;|code-block|syntax|javascript|2152867|编辑：|2152868|这里有一种更简单的方式来表达逻辑。如果使用正确的索引，它的性能可能会更好：|2152869|SELECT+d.*,+t.*
FROM+tbl_device+d+INNER+JOIN
+++++tbl_temperature+t
+++++ON+d.ID+=+t.DevID
WHERE+t.ID+>=+(SELECT+t2.ID
+++++++++++++++FROM+tbl_temperature+t2
+++++++++++++++WHERE+t2.DevId+=+t.DevId
+++++++++++++++ORDER+BY+t2.ID+DESC
+++++++++++++++OFFSET+2+LIMIT+1
++++++++++++++);|2152870|为了提高性能，这可以在tbl_temperature(devid,+id)上使用索引。|2152871|entityMap^0|O|C|0|0|0|0|0|0|B|Q|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|11|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|12|8|@]|D|@]|E|$]]|$1|Q|3|R|5|J|7|13|8|@]|D|@]|E|$K|L]]|$1|S|3|T|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|U|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|V|$]]

The simplest way is to use ANSI-standard window functions (<code>row_number()</code> in particular). But MySQL does not support those (yet).

In MySQL, probably the best way is to use variables:

<pre><code>SELECT . . .
FROM tbl_device d JOIN
 (SELECT t.*,
 (@rn := if(@d = t.devid, @rn + 1,
 if(@d := t.devid, 1, 1)
 )
 ) as rn
 FROM (SELECT t.*
 FROM tbl_temperature t
 ORDER BY DevID, id DESC
 ) t CROSS JOIN
 (SELECT @d := -1, @rn := 0) params
 ) t
 ON tbl_device.ID = tbl_temperature.DevID
WHERE rn &lt;= 3;
</code></pre>

EDIT:

Here is a simpler way to express the logic. It might be performant with the right indexes:

<pre><code>SELECT d.*, t.*
FROM tbl_device d INNER JOIN
 tbl_temperature t
 ON d.ID = t.DevID
WHERE t.ID &gt;= (SELECT t2.ID
 FROM tbl_temperature t2
 WHERE t2.DevId = t.DevId
 ORDER BY t2.ID DESC
 OFFSET 2 LIMIT 1
 );
</code></pre>

For performance, this can use an index on <code>tbl_temperature(devid, id)</code>.

blocks|key|2029709|text|它应该是这样的|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2029710|SELECT+*+FROM+`tbl_device`+
INNER+JOIN+`tbl_temperature`+ON+tbl_device.ID+=+tbl_temperature.DevID
ORDER+BY+tbl_temperature.DevID+DESC
LIMIT+3+OFFSET+0|code-block|syntax|javascript|2029711|order列可以与我的示例中的不同。谷歌MySQL限制偏移量|2029712|或者，如果您只需要从一个表中获得最后三个结果，然后将其连接到另一个表，那么它将类似于|2029713|SELECT+*+FROM+tbl_device+INNER+JOIN
(SELECT+....+FROM+other_table+ORDER+BY+your_column+DESC+LIMIT+3+OFFSET+0)+as+
T1+ON+T1.id+=+tbl_device.ID|2029714|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|S|8|@]|9|@]|A|$E|F]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

It should be something like

<pre><code>SELECT * FROM `tbl_device` 
INNER JOIN `tbl_temperature` ON tbl_device.ID = tbl_temperature.DevID
ORDER BY tbl_temperature.DevID DESC
LIMIT 3 OFFSET 0
</code></pre>

The order column can be not the same as in my example. Google MySQL LIMIT OFFSET

Or if you need to get only three last results from one of your tables then join it to another then it will be something like

<pre><code>SELECT * FROM tbl_device INNER JOIN
(SELECT .... FROM other_table ORDER BY your_column DESC LIMIT 3 OFFSET 0) as 
T1 ON T1.id = tbl_device.ID
</code></pre>

I Hope someone could help me.

My Query.

<pre><code>SELECT * FROM `tbl_device` 
INNER JOIN `tbl_temperature` ON tbl_device.ID = tbl_temperature.DevID
</code></pre>

Result.

<a href="https://i.stack.imgur.com/QCrnH.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QCrnH.jpg" alt="Query Results"></a>

How can get something like this as shown in the photo on the link.

<a href="https://i.stack.imgur.com/6FWi3.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6FWi3.jpg" alt="tbl_device.DevID"></a>

I need to get only the last 3 result of the tbl_device.DevID

I apologize for my bad english, it's really hard to explain. Any help is realy much appreciated.

Thanks a lot!

mysql inner join get only the last 3 equals

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。

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我希望有人能帮我。我的问题。SELECT * FROM `tbl_device` INNER JOIN `tbl_temperature` ON tbl_device.ID = tbl_temperature.DevID结果。​​如何才能获得如链接上的照片所示的东西。​​我只需要获取tbl_device.DevID的最...

问mysql内部连接仅获取最后3个等于
EN

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