mysql分组排序取最新的数据

mysql中按某个字段分组获取最新的数据的场景还是很多的。如果获取用户最新的获取车系记录等等。

关联查询方法

这里依赖了的int类型的主键，作为关联查询的key。

SELECT t1.*
FROM car_browsed_record t1
JOIN (
    SELECT car_series_id, MAX(id) AS max_id
    FROM car_browsed_record
    GROUP BY car_series_id
) t2
ON  t1.id = t2.max_id
order by id desc 

窗口函数

貌似mysql8才被支持，原理就是先按PARTITION BY分区并指定字段排序后得到一个rownum。那么row_num最小的也就是我们需要获取的这一条数据

SELECT *
FROM (
    SELECT *, ROW_NUMBER() OVER (PARTITION BY car_series_id ORDER BY id DESC) AS row_num
    FROM car_browsed_record
) t
WHERE t.row_num = 1
order by id desc