計算查詢中的百分比 - 訪問SQL

Question

我試圖量化一些東西。這裏是（簡化當然）樣本：

tblParent: { Number, Name } 
tblChild: { Number, Name, ParentNumber, Criterion } 

我想指望孩子具有相同ParentNumber總數（方便使用GROUP BY和一個Count（1）），但問題比較該數字與ParentNumber的的子女人數相同。

這是我到目前爲止有：

SELECT "Criterion = 1" AS CritDesc, 
COUNT(1) AS Total, 
ParentNumber AS Parent, 
(COUNT(1)/(SELECT Total FROM [TotalCountingQuery])) AS Percentage 
FROM tblChild 
WHERE Criterion = 1 
GROUP BY ParentNumber; 

[TotalCountingQuery]簡單地計算所有與每個ParentNumber兒童，並把該總進Total

SELECT COUNT(1) AS Total FROM tblChild GROUP BY ParentNumber; 

所以我嘗試使用總數和找出有多少（作爲百分比）具有標準= 1。但是由於它使用的是子查詢，所以子查詢不能返回多個Total。我需要它返回每個ParentNumber的總數，用於具有該ParentNumber的每個Child的Percentage calc。

最終結果應該是：

CritDesc | Total | Parent | Percentage 
``````````````````````````````````````````````````````` 
Criterion=1|  2  | 45011  |  0.333 // Means there should be 6 Children with 45011 as parent 
Criterion=1|  4  | 43255  |  0.9 
Criterion=1|  1  | 59056  |  0.44 

我有幾個這些查詢我的工會在一份報告中，產生一份完整的報告，由家長進行分組，顯示所有的家長都「的標準= X」。這是工作，我只需要上述工作。

想法？

編輯：我在加入用於此目的的嘗試：

SELECT "Criterion=1" AS CritDesc, 
COUNT(c.Number) AS Total, 
ParentNumber AS Parent, 
COUNT(c.Number)/q.Total AS Percentage 
FROM tblChild AS c INNER JOIN tblParent AS q ON c.ParentNumber = q.Number 
GROUP BY ParentNumber 

此拋出：You tried to execute a query ... 'Count(1)/q.Total' as part of an aggregate function。將它添加到group-by語句拋出Cannot have aggregate function in GROUP BY ...

Answer 1

你的子查詢中沒有where子句，從而計算所有記錄，但你可以不用子查詢

SELECT 
    "Criterion = 1" AS CritDesc, 
    SUM(IIf(Criterion = 1, 1, 0)) AS NumCrit, 
    COUNT(*) AS TotalNum, 
    SUM(IIf(Criterion = 1, 1, 0))/COUNT(*) AS Percentage, 
    ParentNumber AS Parent 
FROM 
    tblChild 
GROUP BY 
    ParentNumber; 

注：我放棄了WHERE子句。相反，我正在計數符合標準的記錄，總計1爲Criterion = 1和0。這使我可以在Count(*)的同時獲得每ParentNumber的總數。

---

UPDATE

你可能想要得到，沒有孩子以及家長的結果。在這種情況下，你可以使用一個外部聯接

SELECT 
    "Criterion = 1" AS CritDesc, 
    SUM(IIf(C.Criterion = 1, 1, 0)) AS NumCrit, 
    COUNT(C.Number) AS TotalNumOfChildren, 
    SUM(IIf(C.Criterion = 1, 1, 0))/COUNT(*) AS Percentage, 
    P.Number AS Parent 
FROM 
    tblChild AS C 
    LEFT JOIN tblParent AS P 
     ON C.ParentNumber = P.Number 
GROUP BY 
    P.Number; 

注意，我讓孩子的總數Count(C.Number)爲Count(*)也要算沒有孩子的記錄，以及在這種情況下，產生1。然而，在計算百分比時，爲了避免被零除，我除以Count(*)。在這種情況下結果仍然正確，因爲Criterion = 1的記錄總和將爲零。

Answer 2

如果您在MS Access中工作，則可以用父母的DCount進行劃分。

Total/DCount("Parent","Table","Parent=" & Parent) 

您還可以創建一個數查詢

SELECT Parent, Count(Parent) FROM Table GROUP BY Parent 

然後兩個查詢添加到設計網格上的家長加入他們。