PHP / MySQL - 获取最近3个唯一更新的记录

Question

我想知道是否有人可以提供帮助。

我需要编写一个获取最后3个“创建”记录的查询，但是它们的UID必须是唯一的，例如，我的mysql字段看起来像这样

uid    created
19     2012-02-01 01:08:43
18     2012-02-31 17:07:21
19     2012-02-31 16:07:20
20     2012-02-31 13:03:00

好的，所以我想要创建最后3个uid ...但是它们必须是唯一的uid，所以同样的uid不能出现两次。

干杯

Answer 1

这应该这样做

SELECT * FROM ( SELECT * FROM tablename ORDER BY uid, created DESC ) ordered GROUP BY uid

Answer 2

您可以使用此查询选择最后3个ID：

SELECT * FROM ( SELECT * FROM table ORDER BY uid, created DESC ) AS selected GROUP BY uid LIMIT 3

逻辑是：uid字段按降序排列表，限制为3个字段。

Answer 3

SELECT * 
FROM table 
ORDER BY created DESC 
GROUP BY uid LIMIT 0,3

Answer 4

使用Distinct和Group by获取您之后的内容：

SELECT DISTINCT * FROM table GROUP BY uid;

这将为您提供所有独特的UID。 然后在那里添加你的ORDER BY以确保你获取最后的记录。

Answer 5

SELECT uid
     , MAX(created) AS max_created
FROM tableX
GROUP BY uid
ORDER BY max_created DESC
LIMIT 3