根据 when 语句中的不同日期参数多次运行查询并合并结果，而不是多个 UNION ALL

如何解决根据 when 语句中的不同日期参数多次运行查询并合并结果，而不是多个 UNION ALL

我希望从核心表中提取和合并类似的聚合，但在 WHEN 语句中定义的日期期间有所不同。我通常会这样做：

with base as (
  select 
    event_datetime,event_location,event_uuid
  from events_table
)

select
  "last_30_days" as period,count(distinct event_uuid) as number_events
from base
where event_datetime >= current_date - 30
group by event_location

union all

select
  "last_60_days" as period,count(distinct event_uuid) as number_events
from base
where event_datetime >= current_date - 60
group by event_location

union all

select
  "all_time" as period,count(distinct event_uuid) as number_events
from base
where event_datetime >= current_date - 10000
group by event_location

有谁知道是否有办法避免必须维护三个单独的子查询，并让一个子查询根据不同的时间段重新运行并合并结果（产生与上述代码相同的输出）？

解决方法

考虑以下方法

select 
  period,event_location,count(distinct if(event_datetime >= current_date - days,event_uuid,null)) as number_events
from base,unnest([
  struct('last_30_days' as period,30 as days),struct('last_60_days',60),struct('all_time',10000)
]) 
group by period,event_location