Question

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

Devices/Table:

        /*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:

     /*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 :

     /* 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

Answer 1

You can use this solution:

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