最近需要通过sql得出根据评论时间对帖子进行排序的结果集,由于很长时间都没有用sql,所以费了近两天时间才把语句写出来,但只是完成了功能,效率不是很好,先将就用上,以后再慢慢优化吧!
select * from categories as ca,
(select * from recipes as r1 where r1.date>=all
(select r2.date from recipes as r2 where r1.category_id=r2.category_id))as re
where ca.id=re.category_id order by re.date desc;