检索每个组中的最后一条记录- MySQL

有一个表消息，其中包含如下所示的数据:

Id   Name   Other_Columns
-------------------------
1    A       A_data_1
2    A       A_data_2
3    A       A_data_3
4    B       B_data_1
5    B       B_data_2
6    C       C_data_1

如果我按名称从消息组中运行查询select *，我将得到如下结果:

1    A       A_data_1
4    B       B_data_1
6    C       C_data_1

哪个查询将返回以下结果?

3    A       A_data_3
5    B       B_data_2
6    C       C_data_1

也就是说，应该返回每个组中的最后一条记录。

目前，这是我使用的查询:

SELECT
  *
FROM (SELECT
  *
FROM messages
ORDER BY id DESC) AS x
GROUP BY name

但这看起来效率很低。还有其他方法可以达到同样的效果吗?

当前回答

你也可以从这里看。

http://sqlfiddle.com/ !9 / ef42b / 9

第一个解决方案

SELECT d1.ID,Name,City FROM Demo_User d1
INNER JOIN
(SELECT MAX(ID) AS ID FROM Demo_User GROUP By NAME) AS P ON (d1.ID=P.ID);

第二个解决方案

SELECT * FROM (SELECT * FROM Demo_User ORDER BY ID DESC) AS T GROUP BY NAME ;

2015-09-28 09:07:12

其他回答

Hi @Vijay Dev如果你的表消息包含Id，这是自动增加主键，然后在主键上获取最新的记录，你的查询应该如下所示:

SELECT m1.* FROM messages m1 INNER JOIN (SELECT max(Id) as lastmsgId FROM messages GROUP BY Name) m2 ON m1.Id=m2.lastmsgId

2014-10-21 14:08:16

SELECT 
  column1,
  column2 
FROM
  table_name 
WHERE id IN 
  (SELECT 
    MAX(id) 
  FROM
    table_name 
  GROUP BY column1) 
ORDER BY column1 ;

2014-04-11 06:55:00

试试这个:

SELECT jos_categories.title AS name,
       joined .catid,
       joined .title,
       joined .introtext
FROM   jos_categories
       INNER JOIN (SELECT *
                   FROM   (SELECT `title`,
                                  catid,
                                  `created`,
                                  introtext
                           FROM   `jos_content`
                           WHERE  `sectionid` = 6
                           ORDER  BY `id` DESC) AS yes
                   GROUP  BY `yes`.`catid` DESC
                   ORDER  BY `yes`.`created` DESC) AS joined
         ON( joined.catid = jos_categories.id )

2011-07-15 02:05:08

根据您的问题，下面的查询将很好地工作。

SELECT M1.* 
FROM MESSAGES M1,
(
 SELECT SUBSTR(Others_data,1,2),MAX(Others_data) AS Max_Others_data
 FROM MESSAGES
 GROUP BY 1
) M2
WHERE M1.Others_data = M2.Max_Others_data
ORDER BY Others_data;

2011-11-18 20:19:44

我在https://dzone.com/articles/get-last-record-in-each-mysql-group找到了最好的解决方案

select * from `data` where `id` in (select max(`id`) from `data` group by `name_id`)

2020-10-01 12:25:59

检索每个组中的最后一条记录- MySQL

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