Question

我有三个这样的查询：

select count(*) as customers, created_at::date as date from table1 where subscription_ends_at IS NOT NULL group by created_at::date order by created_at::date ASC

select count(*) as customers, created_at::date as date from table2 where subscription_ends_at IS NOT NULL group by created_at::date order by created_at::date ASC

select count(*) as customers, created_at::date as date from table3 where subscription_ends_at IS NOT NULL group by created_at::date order by created_at::date ASC

我需要的是最后两列：三个表中的日期和总计customers。我尝试了一个子查询，但是不确定如何正确放置GROUP BY而不出错。我尝试过这样的事情：

select ((select count(*) as customers, created_at::date as date from table1 where subscription_ends_at IS NOT NULL group by created_at::date order by created_at::date ASC)+(select count(*) as customers, created_at::date as date from table2 where subscription_ends_at IS NOT NULL group by created_at::date order by created_at::date ASC)+(select count(*) as customers, created_at::date as date from table3 where subscription_ends_at IS NOT NULL group by created_at::date order by created_at::date ASC)) AS SumCount

Answer 1

我想您可以使用union all合并表中的数据，然后执行汇总

select t.date, count(*)
from (
    select  created_at::date as date from table1 where subscription_ends_at IS NOT NULL 
    union all
    select  created_at::date as date from table2 where subscription_ends_at IS NOT NULL
    union all
    select created_at::date as date from table3 where subscription_ends_at IS NOT NULL
) t
group by t.date
order by t.date

从包括WHERE语句和GROUP BY在内的不同表中添加COUNT（*）

1 个答案: