如何在一个查询中合并两个聚合函数？

Question

我正在尝试分析每天的平均值（每个创建的内容共＃条评论）。我有一个清单 1.评论数， 2.创建的内容数 天明智。但是我无法将它们全部输出到同一表的列中。

Google BigQuery。

问题是-

代码1：

当我将前一列的结果合并到下一列时，它会显示无法识别的名称 comment_per_UGC。

代码2：

如果我使用avg(sum(comments)/count(distinct (postId)))，则会出现错误消息，提示不允许使用聚合函数进行聚合。

代码1-

select date_posted, count(*) as Commentors, sum(comments) as comment, 
count(distinct (postId)) as UGC, sum(comments)/count(distinct (postId)) 
as comment_per_UGC, avg(comment_per_UGC) as Overall_Avg_UGC

代码2-

select date_posted, count(*) as Commentors, sum(comments) as comment, 
count(distinct (postId)) as UGC, sum(comments)/count(distinct (postId)) 
as comment_per_UGC, avg(sum(comments)/count(distinct (postId))) as 
Overall_Avg_UGC

预期输出-平均（comment_per_UGC）作为最后一列（第6列）

Answer 1

尝试使用子查询；

    Select date_posted,avg(comment_per_UGC) from (    
    select date_posted, count(*) as Commentors, sum(comments) as comment, 
        count(distinct (postId)) as UGC, sum(comments)/count(distinct (postId)) 
        as comment_per_UGC


    ) t
group by date_posted