求总数后的平均值

Question

我有疑问

output

结果

SELECT language, COUNT(language) AS countx, sum(COUNT(language)) OVER() AS totalcount
FROM table1
where Language is not null
GROUP BY Language

不确定如何从每个组的 countx/totalcount 获得 AVG，所以 1672/1693 和 21/1693。
谢谢。

Answer 1

只要分开：

SELECT language, COUNT(language) AS countx,
       sum(COUNT(language)) OVER () AS totalcount,
       COUNT(language) * 1.0 / sum(COUNT(language)) OVER()
FROM table1
WHERE Language is not null
GROUP BY Language ;

有些数据库做整数除法，这就解释了 * 1.0。