BigQuery：Select 使用 GroupBy 的前 3 天销售额并保存在单独的列中，留下其他列

Question

输入： 得到了Table'A'

Store   Category   Sales   Day
11      aaa        1.5     Sunday
11      aaa        0.5     Monday
11      aaa        2.5     Tuesday
11      aaa        2.0     Wednesday
11      aaa        3.0     Thursday
11      aaa        3.5     Friday
11      aaa        0.5     Saturday
22      bbb        0.5     Sunday
22      bbb        1.5     Monday
22      bbb        2.3     Tuesday
22      bbb        0.3     Wednesday
22      bbb        1.4     Thursday
22      bbb        4.1     Friday
22      bbb        0.2     Saturday

场景： 必须取按商店、类别分组的销售额的平均值并保存在单独的列中，以及选择前 3 个销售日并保存在单独的列中。结果，一行对应一个商店，类别如下示例输出所示。

预期输出：

Store   Category   AvgSales   PeakDay1   PeakDay2   PeakDay3   
11      aaa        1.92       Friday     Thursday   Tuesday
22      bbb        1.47       Friday     Tuesday    Monday

尝试查询：

SELECT
  Store,
  Category,
  avg(Sales) as AvgSales,
  ARRAY_AGG(Sales ORDER BY Sales DESC LIMIT 3)  #but this line will not produce results in 3 separate columns
FROM A
GROUP BY Site, Category

提前致谢！

Answer 1

您可以使用数组聚合，但 row_number() 看起来很简单：

select store, category, avg(sales),
       max(case when seqnum = 1 then day end) as peakday1,
       max(case when seqnum = 2 then day end) as peakday2,
       max(case when seqnum = 3 then day end) as peakday3
from (select store, category, day, 
             row_number() over (partition by store, category order by sales desc) as seqnum
      from a
     ) a
group by store, category;

如果您想将其放入数组列中，您可以使用：

SELECT Store, Category, avg(Sales) as AvgSales,
       ARRAY_AGG(day ORDER BY Sales DESC LIMIT 3) 
FROM A
GROUP BY Site, Category

Answer 2

以下适用于 BigQuery 标准 SQL

#standardSQL
SELECT Store, Category, AvgSales,
  Days[OFFSET(0)] PeakDay1,
  Days[SAFE_OFFSET(1)] PeakDay2,
  Days[SAFE_OFFSET(2)] PeakDay3
FROM (
  SELECT Store, Category, 
    ROUND(AVG(Sales), 2) AvgSales,
    ARRAY_AGG(Day ORDER BY Sales DESC LIMIT 3) Days
  FROM `project.dataset.table` t
  GROUP BY Store, Category
)

如果应用于您问题中的示例数据 - 输出为

Row Store   Category    AvgSales    PeakDay1    PeakDay2    PeakDay3     
1   11      aaa         1.93        Friday      Thursday    Tuesday  
2   22      bbb         1.47        Friday      Tuesday     Monday

BigQuery：Select 使用 GroupBy 的前 3 天销售额并保存在单独的列中，留下其他列

BigQuery: Select top 3 Day of Sales with GroupBy and save in separate columns leaving others

sql

group-by

average

google-bigquery

array-agg