[英]Build time window counters from raw data - Big Query
根据下表考虑有关 2020 年购买的原始事件数据:
BUYER DATE ITEM
Joe '2020-01-15' Dr. Pepper
Joe '2020-02-15' Dr. Pepper
Joe '2020-03-15' Dr. Pepper
Joe '2020-05-15' Dr. Pepper
Joe '2020-10-15' Dr. Pepper
Joe '2020-12-15' Dr. Pepper
我想汇总数据以查看 Joe 在每月移动总和中做了什么,即作为结果获得
BUYER Date Num_Purchases_last_3months
Joe '2020-01-31' 1
Joe '2020-02-31' 2
Joe '2020-03-31' 3
Joe '2020-04-31' 2
.
.
.
Joe '2020-11-31' 1
Joe '2020-12-31' 2
如何在高效查询中获得所需的结果?
您可以使用 window 函数,在本例中, count(*)
的range
为 window 帧规范:
select t.*,
count(*) over (partition by buyer
order by extract(year from date) * 12 + extract(month from date)
range between 2 preceding and current row
) as Num_Purchases_last_3months
from t;
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