今天和昨天同一时间数据Mysq的成本比较；

Question

我具有以下MySQL表的表结构

timestamp  | agg_id | media_cost
1587121200 | 2      | 10
1587121200 | 3      | 5
1587121100 | 2      | 6
1587121200 | 2      | 2
1587341200 | 3      | 5

我必须每小时查询一次，以便它将昨天的成本与今天运行时的成本进行比较，并警告今天的成本是否小于昨天的成本的一半，并按agg_id分组。

我正在使用以下查询作为参考，但不确定如何获得预期的输出

  select 
  today.datetime, 
  100 * (sum(today.cost) - sum(yesterday.cost))/sum(today.cost) as pctdiff, 
  sum(today.cost) as today, 
  sum(yesterday.cost) as yesterday 
  from (
  select datetime, cost, id 
  from table 
  where datetime between curdate() and now() - interval 1 hour
  ) as today 
  join (
  select datetime, cost, id 
  from table 
  where left(datetime,10) = curdate() - interval 1 day 
   ) as yesterday on today.id=yesterday.id 
  group by today.datetime 
  order by today.datetime asc ;

有人可以在这里引导我