不能嵌套聚合操作答案

【问题标题】：Cannot nest aggregate operations不能嵌套聚合操作
【发布时间】：2015-08-26 08:06:49
【问题描述】：

我正在尝试运行以下查询：

Select T, COUNT(T) as CountOf, (COUNT(T)*100)/(SUM(COUNT(T))) AS percen FROM
(
select prod as T, x,y,z from table1
UNION ALL select prod as T, x,y,z from table2
UNION ALL select prod as T, x,y,z from table3
)
AS m
GROUP BY T ORDER BY COUNT(T) DESC;

上面的查询给出了错误。我能够在没有第三个参数的情况下成功运行查询，即(COUNT(T)*100)/(SUM(COUNT(T))) AS percent（计算第二个参数的百分比分布，即CountOf）

但是当我包含百分比参数时，它会出错。对此的任何帮助将不胜感激。

【问题讨论】：

MySQL、SQLServer 和 teradata 都是不同的产品——您使用的是哪一种？这与您的问题直接相关 - 在 SQLServer 中比在 MySQL 中执行您想要的（我认为）有一种更简单的方法。

标签： mysql teradata

【解决方案1】：

我不喜欢使用 distinct 但如果你使用 sql server 你可以试试

Select DISTINCT T, COUNT(*) OVER (PARTITION BY T) as CountOf,  ((COUNT(*) OVER (PARTITION BY T) * 100) / COUNT(*) OVER ()) AS percen FROM
(
select prod as T, x,y,z from table1
UNION ALL select prod as T, x,y,z from table2
UNION ALL select prod as T, x,y,z from table3
)
AS m

CTE 选项

WITH cteUnion AS (
    SELECT prod AS T, x,y,z FROM table1
    UNION ALL 
    SELECT prod AS T, x,y,z FROM table2
    UNION ALL 
    SELECT prod AS T, x,y,z FROM table3
),
cteUnionWithTotalCount AS (
    SELECT *, COUNT(*) OVER () AS TotalCount FROM cteUnion
)
SELECT  T, COUNT(*) AS CountOf, ((COUNT(*) * 100)/ TotalCount) AS percen
FROM    cteUnionWithTotalCount
GROUP BY T, TotalCount
ORDER BY COUNT(*)

【讨论】：

你好，第二个参数变成每行的1，第三个参数，即每行的百分比变成0。仍然无法弄清楚。
你还在用你的group by吗？
是的，我正在使用 group by 子句
取出group by子句
嗨，谢谢。我想到了。唯一的问题是许多值都是 0，因为它试图将 106 行分配为百分比值。所以值非常高的值得到一个百分比数字，其余的都得到 0。

【解决方案2】：

您需要将SUM 更改为SUM OVER，但MySQL 不支持：

SELECT T, COUNT(T) AS CountOf, 
   (COUNT(T)*100)/(SUM(COUNT(T)) OVER ()) AS percen
FROM
 (
   SELECT prod AS T, x,y,z FROM table1
   UNION ALL 
   SELECT prod AS T, x,y,z FROM table2
   UNION ALL 
   SELECT prod AS T, x,y,z FROM table3
  ) AS m
GROUP BY T 
ORDER BY COUNT(T) DESC;

【讨论】：