# 查询多少类商品贡献了80%的销售额
select  item_category,
        sum(amount) as 销售额,
        sum(sum(amount))over(order by sum(amount) desc) as 累计销售额
        sum(sum(amount))over(order by sum(amount) desc)/(select sum(amount) from userbehavior_new where behavior_type ='buy') as 累计占比
from userbehavior_new
where behavior_type ='buy'
group by item_category;

select count(*) as 类目数
from (select item_category,
           sum(amount) as 销售额,
           sum(sum(amount))over(order by sum(amount) desc) as 累计销售额,
           sum(sum(amount))over(order by sum(amount) desc)/(select sum(amount) 
                                                              from userbehavior_new 
                                                              where behavior_type ='buy') as 累计销售额占比
      from userbehavior_new
      where behavior_type ='buy'
      group by item_category) as T
where 累计销售额占比 <= 0.8;