参考案例:
1、将文章按类型的分组,并获取类型分组中最新的一篇文章
select author,max(`updated_at`) as updated_at from articles
group by category_id
order by updated_at desc
2、将文章按类型的分组,并获取类型分组中阅读量最小的一篇文章
select author,min(`read_cnt`) as read_cnt from articles
group by category_id
order by read_cnt
实战测试:
-- 获取每一个房间的最新的一条数据值
SELECT integral_num,room_code,MAX(CRE_DATE)
FROM jc_devices_card_integral
GROUP BY room_code
ORDER BY CRE_DATE DESC;
结果:
-- 全量数据
SELECT integral_num,room_code,CRE_DATE
FROM jc_devices_card_integral
ORDER BY cre_date DESC ;
根据两条数据的结果集很明显发现 .是我想要的数据!!仅供参考..