产品贡献定量分析（帕累托分析）(累积销售额占比=累积销售额/总销售额)
select *
from
(select
item_category,
sum(amount) as 销售额,
sum(sum(amount)) over(order by sum(amount) desc) as 累积销售额,
#当over中指定了排序,但是没有指定滑动窗口范围时,默认计算当前分区内第一行到当前行(排序字段)取值范围内的记录
sum(sum(amount)) over() as 总销售额,
#当over中没有指定分区、排序和滑动窗口范围时,表中所有记录为一个区,默认计算当前分区内的所有记录
sum(sum(amount)) over(order by sum(amount) desc)/sum(sum(amount)) over() as 累积销售额占比
from userbehavior_new
where behavior_type='buy'
group by item_category) as t
where 累积销售额占比<=0.8;