[英]MySQL Retrieving last record from table1 and join data from table 2
I have two table (below codes) , want to retrieve last row of trackers_data
table and GROUP BY tracker_id
and (join) information of each tracker_id
from Table Devices
我有两个表(下面的代码),想要检索
trackers_data
表的最后一行和GROUP BY tracker_id
并从表Devices
tracker_id
每个tracker_id
( GROUP BY tracker_id
)信息
Devices/Table: 设备/表:
/*Table: devices*/
id tracker_id name device_name
-----------------------------------
1 1242 Driver A Benz
2 1255 Driver B Volvo
3 1256 Driver C BMW
Trackers_data/Table: Trackers_data /表:
/*Table: trackers_data*/
id tracker_id longitude latitude
-------------------------------------
5 1255 53.25 11.52
6 1255 52.63 11.63
7 1242 52.23 13.11
8 1242 52.25 15.27
9 1242 54.63 13.86
Example/Results should like below : 示例/结果应如下所示:
/* Results */
id tracker_id lonitude latitude name device_name
6 1255 52.63 11.63 Driver B Volvo
9 1242 54.63 13.86 Driver C BMW
You can use this solution: 您可以使用以下解决方案:
SELECT b.*, c.name, c.device_name
FROM (SELECT MAX(id) AS id FROM trackers_data GROUP BY tracker_id) a
JOIN trackers_data b ON a.id = b.id
JOIN devices c ON b.tracker_id = c.tracker_id
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