計算總和中的小計的比例

Question

我已經探索並發現了許多不同的示例，但其中沒有一個似乎可行。我得到的最接近的是over（），但由於語法錯誤而失敗。

考慮以下查詢。

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

結果是標識 s的出現的金額值的數量和名單。這很好。不過，我還想說明每個總和的總和有多大。我試過以下。

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

它失敗，我不知道如何解決它（主要是因爲超過啄更多的是猜測比穩定的知識）。

Answer 1

您需要檢索總量的所有記錄，你可以用下面的操作：

SELECT sum(Amount) FROM MyTable

，並把那在您的查詢的除數爲sum(Amount)。因此，您的查詢看起來象下面這樣：

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數據類型是INT，您可能需要轉換比率爲decimal數據類型。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 

[編輯]：如果你想使用OVER條款，我建議你多了一個子查詢：

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