我为所有行得到相同的百分位数答案

【问题标题】：I get the same value percentile for all rows我为所有行得到相同的百分位数
【发布时间】：2021-10-11 09:09:38
【问题描述】：

对于每个行政区，每个十字路口受伤人数的第 90 个百分位数是多少？

我有 borough 列，其中包含受伤人数的列，我将其汇总为一列。我需要找到受伤人数的 90%。它只给了我一个价值。我需要为每一行获取不同的值（或者我错了吗？）

select distinct borough,count(num_of_injured) as count_all, PERCENTILE_CONT(num_of_injured, 0.9 RESPECT NULLS) OVER() AS percentile90

from`bigquery-public-data.new_york.nypd_mv_collisions` c cross join
  unnest(array[number_of_persons_injured,number_of_pedestrians_injured,number_of_motorist_killed,number_of_cyclist_injured]
    )num_of_injured

where borough!='' 

group by borough,num_of_injured

order by count_all desc

limit 10;

table

感谢您的帮助！

【问题讨论】：

标签： sql group-by google-bigquery subquery percentile

【解决方案1】：

如果您查看每个受伤人数按行政区划分的计数，那么超过 90% 是0：

select  borough, num_of_injured, count(*),
        count(*) / sum(count(*)) over (partition by borough)
from`bigquery-public-data.new_york.nypd_mv_collisions` c cross join
    unnest(array[number_of_persons_injured,number_of_pedestrians_injured,number_of_motorist_killed,number_of_cyclist_injured]
          ) num_of_injured 
group by 1, 2
order by 1, 2;

因此，第 90 个百分位是 0。

【讨论】：