group by查询每组时间最新的一条记录

 

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最近需要查询每组时间最新的记录

表如下：

目标结果是：

 

 

一开始的想法：

select * from

 

(select * from log where account_id = 45 order by shop_id,create_time desc)  w

 

group by w.shop_id

 

这种写法看着没毛病，但是查询出来不是每组最新的一条

 

 

正确的写法很多这里说个认为比较简单的

select * from log where id in

 

(select SUBSTRING_INDEX(GROUP_CONCAT(id order by create_time desc), ',', 1)   from log where account_id = 45 group by shop_id)

 

分部解读：

根据条件查询出分组的所有按时间降序的记录id并拼接

1.select GROUP_CONCAT(id order by create_time desc) from log where account_id = 45 group by shop_id

 

 

2. 查询每个分组中时间最新的那条记录的id

select SUBSTRING_INDEX(GROUP_CONCAT(id order by create_time desc), ',', 1)   from log where account_id = 45 group by shop_id

 

3.

select * from log where id in

 

(select SUBSTRING_INDEX(GROUP_CONCAT(id order by create_time desc), ',', 1)   from log where account_id = 45 group by shop_id)