Postgresql：尝试获得过去10天的平均值

Question

Select avg(last_10_count) AS last_10_avg
(Select count(*)
from dim_user
where effective_date ::date > current_date -10
group by effective_date ::date) AS last_10_count

当我刚运行内联查询时，我得到了所需的结果，但是当我运行整个查询时，它会抛出以下错误：

ERROR: function avg(record) does not exist
LINE 1: Select avg(last_10_count) AS last_10_avg
HINT: NO function matches the given name and arguement types.
      You might need to add explicit type casts.
************Error***************
ERROR: function avg(record)  does not exit
SQL state: 42883

Answer 1

试试这个

Select avg(last_10_count) AS last_10_avg from 
(Select count(*) as last_10_count
from dim_user
where effective_date::date  > current_date -10
group by effective_date :: date) Z