获得每组最新记录及其所有值

Question

ID | serial | created_at | data 1..45
1  | 001    | timestamp  |  ....
2  | 002    | timestamp  |  ....
3  | 003    | timestamp  |  ....
4  | 001    | timestamp  |  ....
5  | 002    | timestamp  |  ....
6  | 001    | timestamp  |  ....
7  | 003    | timestamp  |  ....
8  | 004    | timestamp  |  ....
9  | 001    | timestamp  |  ....

我希望得到ID为9,8,7,5的结果，因为我需要每个序列的最新行

=> "SELECT * FROM `rig_stats` GROUP BY `rig_stats`.`serial` ORDER BY `rig_stats`.`id` DESC"

然而这给了我第一次出现，按id命令desc所以结果是1 2 3 8并且不是我想要的。

使用mysql Ver 14.14 Distrib 5.7.21, for Linux (x86_64)

Answer 1

您可以加入子查询，查找每个序列的最新行：

SELECT s1.*
FROM serial s1
INNER JOIN
(
    SELECT serial, MAX(created_at) AS max_created_at
    FROM serial
    GROUP BY serial
) s2
    ON s1.serial = s2.serial AND
       s1.created_at = s2.max_created_at;