计算总和中的小计的比例

Question

我已经探索并发现了许多不同的示例，但其中没有一个似乎可行。我得到的最接近的是over（），但由于语法错误而失败。

考虑以下查询。

select Id, 
    count(*) as Count, 
    sum(Amount) as Sum 
from MyTable 
group by Id 

结果是标识 s的出现的金额值的数量和名单。这很好。不过，我还想说明每个总和的总和有多大。我试过以下。

select Id, 
    count(*) as Count, 
    sum(Amount) as Sum, 
    sum(Amount)/sum(Amount) over() as Ratio 
from MyTable 
group by Id 

它失败，我不知道如何解决它（主要是因为超过啄更多的是猜测比稳定的知识）。

Answer 1

您需要检索总量的所有记录，你可以用下面的操作：

SELECT sum(Amount) FROM MyTable

，并把那在您的查询的除数为sum(Amount)。因此，您的查询看起来象下面这样：

select Id, 
     count(*) as Count, 
     sum(Amount) as Sum, 
     sum(Amount)/(SELECT sum(Amount) FROM MyTable) as Ratio 
from  MyTable 
group by Id 

如果您Amount数据类型是INT，您可能需要转换比率为decimal数据类型。例如：

select Id, 
     count(*) as Count, 
     sum(Amount) as Sum, 
     CAST (sum(Amount) AS NUMERIC(10,2))/(SELECT sum(Amount) FROM MyTable) as Ratio 
from  MyTable 
group by Id 

[编辑]：如果你想使用OVER条款，我建议你多了一个子查询：

SELECT [Id], [Count], [Sum], [SUM]/SUM([SUM]) OVER (PARTITION BY 1) 
FROM 
(
     select Id, 
        count(*) as Count, 
        sum(Amount) as Sum    
     from  MyTable 
     group by Id 
) as t