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mysql - 如何将 order by 和 group by 结合在一起？条件：按一列按另一列分组

问题描述

我对 MySQL 中的 order by 和 group by 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（Order by Creation desc）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 |

当我使用order by 和 group by 组合时，

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 |
+-------------+-----------+-----------+----------------------------+

但正如您在上面的结果中看到的那样，我得到了错误的结果，我期待最新更新的 lat、lng列，如下所示。

+-------------+-----------+-----------+----------------------------+
| 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 |
+-------------+-----------+-----------+----------------------------+

标签： mysqlgroup-bysql-order-by

解决方案

这是期待最新更新 la 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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