我在MySQL中按顺序和按组合有一个问题。以下是我的表结构。
+-------------+-----------+-----------+----------------------------+
| driver_id | lat | lng | creation |
+-------------+-----------+-----------+----------------------------+
| TDRV-000021 | 18.659180 | 73.756480 | 2019-03-13 09:21:39.225873 |
| TDRV-000021 | 18.659180 | 73.756480 | 2019-03-15 12:30:09.608296 |
| TDRV-000021 | 18.659135 | 73.756445 | 2019-03-10 15:38:37.954508 |
当我使用以下SQL命令（按创建顺序排序）时，
select driver_id, lat, lng, creation from `tabReal Time Location` order by creation desc;
我得到以下结果，
+-------------+-----------+-----------+----------------------------+
| driver_id | lat | lng | creation |
+-------------+-----------+-----------+----------------------------+
| TDRV-000021 | 20.659180 | 73.756480 | 2019-03-16 08:13:41.155528 |
| TDRV-000021 | 18.659180 | 73.756480 | 2019-03-15 19:44:06.206690 |
| TDRV-000021 | 18.659180 | 73.756480 | 2019-03-15 19:36:25.571260 |
| TDRV-000021 | 18.659180 | 73.756480 | 2019-03-15 19:35:55.115124 |
| TDRV-000021 | 18.659180 | 73.756480 | 2019-03-15 19:35:46.281953 |
| TDRV-000021 | 18.659180 | 73.756480 | 2019-03-15 19:35:00.986849 |
| TDRV-000021 | 18.659180 | 73.756480 | 2019-03-15 19:33:38.370099 |
| TDRV-000021 | 18.659180 | 73.756480 | 2019-03-15 19:32:57.589272 |
| TDRV-000021 | 18.659180 | 73.756480 | 2019-03-15 19:30:24.582391 |
| TDRV-000021 | 18.659180 | 73.756480 | 2019-03-15 19:29:23.809564 |
当我用来合并订单依据和分组依据时，
select driver_id, lat, lng, creation from `tabReal Time Location` group by driver_id order by creation desc;
+-------------+-----------+-----------+----------------------------+
| driver_id | lat | lng | creation |
+-------------+-----------+-----------+----------------------------+
| TDRV-000027 | 18.659180 | 73.756480 | 2019-03-15 13:47:37.338828 |
| TDRV-000021 | 18.659180 | 73.756480 | 2019-03-13 09:21:39.225873 |
+-------------+-----------+-----------+----------------------------+
但是正如您在上述结果中看到的那样，我得到了错误的结果，我期望下面是最新更新的 lat，lng列。
+-------------+-----------+-----------+----------------------------+
| driver_id | lat | lng | creation |
+-------------+-----------+-----------+----------------------------+
| TDRV-000021 | 20.659180 | 73.756480 | 2019-03-16 08:13:41.155528 |
| TDRV-000027 | 20.659180 | 90.756480 | 2019-03-15 14:07:41.543089 |
+-------------+-----------+-----------+----------------------------+
这是期待最新更新的消息的一种方法
select t.driver_id, lat, lng, order_id from `tabReal Time Location` t INNER JOIN (select max(creation) as latest_date,driver_id FROM `tabReal Time Location` group by driver_id)d ON t.creation= d.latest_date and d.driver_id = t.driver_id;
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我来说两句