我有以下名为 messages 的数据库表，其中包含以下列:
thread_id, sender_id, receiver_id, date
例子:
+-----------+------------+-------------+-------------+
| thread_id | sender_id | receiver_id | date |
+----------------------+-----------+-----------------+
| 1 | 1 | 2 | 11/06/2015 |
| 1 | 2 | 1 | 14/06/2015 |
| 1 | 1 | 2 | 14/06/2015 |
| 1 | 2 | 1 | 20/06/2015 |
| 2 | 1 | 3 | 12/06/2015 |
| 3 | 4 | 2 | 19/06/2015 |
| 3 | 2 | 2 | 20/06/2015 |
+-----------+------------+-------------+-------------+
我需要一个查询，该查询将按最早日期选择唯一的 thread_id 并且 thread_id 存在不止一次。
所以我想要的结果是:
+-----------+--------------+
| thread_id | date |
+-----------|--------------+
| 1 | 11/06/2015 |
| 3 | 19/06/2015 |
+-----------+--------------+
最佳答案
SELECT
MIN(date),thread_id
FROM
messages
GROUP BY
thread_id
HAVING
COUNT(thread_id) > 1
关于sql - 按存在重复项的单列获取唯一行，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/30978929/