Redshift - 按类别查找贡献百分比

Question

我的数据格式如下：

product, person
prod_a, person_1
prod_a, person_2
prod_a, person_3
prod_b, person_1

我试图找出每个人对每种产品的贡献百分比。预期输出是：

product, person, prct
prod_a, person_1, 0.33
prod_a, person_2, 0.33
prod_a, person_3, 0.33
prod_b, person_1, 1

Answer 1

你可以使用窗口函数：

select
    product,
    person,
    1.0 * count(*) over(partition by product, person) 
        / count(*) over(partition by product) as prct
from mytable

如果，如您的示例数据所示，没有重复的(product, person) 元组，那么就简单一点：

select
    product,
    person,
    1.0 / count(*) over(partition by product) as prct
from mytable