早上好
我正在尝试从数据库中获取一组的最新信息，但到目前为止还没有运气。有任何想法吗？我猜该解决方案很容易，但是我真的被困在那里...
数据：
+---------------+----------+-------+------------+---------------------+
| transition_id | field_id | value | changed_by | changed |
+---------------+----------+-------+------------+---------------------+
| 3 | 1 | Data | Mike | 2018-08-13 00:00:00 |
| 3 | 2 | Data | Mike | 2018-08-13 00:00:00 |
| 3 | 3 | Data | Mike | 2018-08-13 00:00:00 |
| 3 | 1 | Data | Mike | 2018-08-20 00:00:00 |
| 4 | 1 | Data | Mike | 2018-08-15 00:00:00 |
+---------------+----------+-------+------------+---------------------+
预期结果：
+---------------+----------+-------+------------+---------------------+
| transition_id | field_id | value | changed_by | changed |
+---------------+----------+-------+------------+---------------------+
| 3 | 2 | Data | Mike | 2018-08-13 00:00:00 |
| 3 | 3 | Data | Mike | 2018-08-13 00:00:00 |
| 3 | 1 | Data | Mike | 2018-08-20 00:00:00 |
| 4 | 1 | Data | Mike | 2018-08-15 00:00:00 |
+---------------+----------+-------+------------+---------------------+
分组： transition_id，field_id
我尝试在表本身上使用左连接，但这仅返回单个项目。
SELECT t1.*
FROM table t1
LEFT JOIN table t2 ON (t1.event = t2.event AND t1.update < t2.update)
WHERE t2.update IS NULL AND t1.event = 81
谢谢您的帮助！ 安德烈
答案 0 :(得分：0)
尝试一下：
select x.* from tablename x
inner join
(select event, item, max(update) as mupdate from tablename
group by event, item)a
on x.event=a.event and x.item=a.item and x.update=a.mupdate