Mysql Distinct 返回所有重复行

Question

我遇到了这个小问题，

当我运行这个查询时，它工作正常，但是 DISTINCT 返回所有不应该的重复值，我只是想知道为什么它会这样。

查询

SELECT DISTINCT `dstuser` , 
DATE_FORMAT( `t` , '%M %e, %Y' ) AS `date`
FROM `mail`

表

+---------------------+---------+---------+---------+---------+--------+
| time                | srcuser | srchost | dstuser | dsthost | size   |
+---------------------+---------+---------+---------+---------+--------+
| 2006-05-12 15:02:49 | phil    | mars    | phil    | saturn  |   4522 |
| 2006-05-11 10:15:08 | barb    | saturn  | tricia  | mars    |  58274 |
| 2006-05-12 12:48:13 | tricia  | mars    | gene    | venus   | 194925 |
| 2006-05-12 15:02:49 | phil    | mars    | phil    | saturn  |   1048 |
| 2006-05-12 12:48:13 | tricia  | mars    | link    | asure   | 524111 |
+---------------------+---------+---------+---------+---------+--------+

返回

+---------+--------------+
| dstuser | date         |
+---------+--------------+
| tricia  | May 11, 2006 |
| gene    | May 12, 2006 |
| phil    | May 12, 2006 |
| tricia  | May 13, 2006 |
| barb    | May 14, 2006 |
| tricia  | May 14, 2006 |
| phil    | May 14, 2006 |
| gene    | May 15, 2006 |
| phil    | May 15, 2006 |
| tricia  | May 15, 2006 |
| barb    | May 16, 2006 |
| tricia  | May 17, 2006 |
| gene    | May 19, 2006 |
+---------+--------------+
13 rows in set (0.00 sec)

Answer 1

DISTINCT 返回dstuser 和date 的所有唯一组合。为了避免重复的用户，请尝试添加 GROUP BY dstuser