1

我有一个表'item_prices'：

resource_id, avg_price, time_stamp, samples

项目每天都会在表格中插入一个新的平均价格。旧平均值不会被删除。

如何查询自昨天平均以来“价格上涨百分比”最高的 10 件商品？我还想检查样本是否 > 10 以确保准确性。

澄清“价格上涨百分比”：

percent_increase = (todays_avg_price - yesterdays_avg_price) / yesterdays_avg_price

例子

resource_id |  avg_price |  time_stamp |  samples

    1           450         1380526003     12
    2           650         1380526002     2
    3           980         1380526001     68

    1           400         1380440003     24
    2           700         1380440002     13
    3           400         1380440001     38

    1           900         1380300003     11
    2           250         1380300002     8
    3           300         1380300001     4

返回

resource id  |  percent_increase

     3              1.45    
     1              0.125
4

2 回答 2

1 
select  
today.resource_id, 
(today.avg_price - yesterday.avg_price) / yesterday.avg_price as percent_increase
from 
item_prices today, 
item_prices yesterday
where today.resource_id = yesterday_resource_id
and   DATE(FROM_UNIXTIME(today.timestamp)) = $today
and   DATE(FROM_UNIXTIME(yesterday.timestamp)) = $yesterday
order by percent_increase desc 
limit 10

这是一个自我加入；为古老的连接语法道歉，这是一个我很难改掉的坏习惯。

于 2013-10-01T16:27:49.120 回答
-1

请尝试以下查询.. 

  select top 1 resource_id,avg_price from item_Prices 
  group by resource_id,avg_price
  having count(resource_id,avg_price)>
  10 order by time_stamp
于 2013-09-30T06:31:14.180 回答