SQL計數通過分組加入

Question

我已經搜索了所有的SQL問題，並且我發現了我不想要的每個版本 - 所以我需要問一下。我處在一個大腦鎖定中 - 知道有一個數字，數字和組合，以及所有連接在一起。

2表

1. CustomerTable的 - 客戶ID，CustQuality（值是良好的客戶，糟糕的客戶，新客戶等）
2. PurchaseTable（PurchID，PurchItem，PurchDate）

我我試圖計算過去30天內好，壞，新客戶的購買次數。

我曾嘗試加入和組數等，我不斷收到：

• GoodCustomer - CustID2 - 1 PURCH
• GoodCustomer - CustID3 - 3 PURCH
• GoodCustomer - CustID4 - 2 PURCH
• BadCustomer - CustID7 - 2 purch
• BadCustomer - CustID1 - 4 purch
• NewCustomer - CustID9 - 1 purch
• NewCustomer - CustID4 - 4 PURCH等等等等

我只是想整體效果

• 3信譽良好的客戶取得6次購買
• 2個不良客戶的數據製作6次購買
• 2新客戶提出了5個Purcahses

然後爲額外的功能...我有第三張表，我需要加入以及。 CustomerLocation

所以（CLID，CLLocation（北，南，東，西）的值），如果我想了解以下斷裂組下來

• 3信譽良好的客戶取得6個採購 - 1個客戶是北，2個客戶提供從南
• 2個不良客戶的數據做6名購買 - 從東5客戶，1西
• 2新客戶取得5個Purcahses - 南
2客戶

而且最後一個新的查詢將... 哪裏CLLocation =南

或者，如果我想按地區查找...

• 1信譽良好的客戶取得3個購買
• 2不良客戶的數據做2個購買
• 0新客戶取得0 Purcahses

我知道我問了很多 - 但是，任何及所有的幫助將非常感謝！

Answer 1

SELECT C.CustQuality, COUNT(DISTINCT c.CustID) AS tot_Customer, COUNT(PurchID) AS tot_Purch 
FROM CustomerTable C, PurchaseTable P 
WHERE C.CustID = P.PurchCustID 
GROUP BY C.CustQuality; 

SELECT C.CustQuality, CL.CLocation, COUNT(DISTINCT c.CustID) AS tot_Customer, COUNT(PurchID) AS tot_Purch 
FROM CustomerTable AS C, PurchaseTable AS P, CustomerLocation AS CL 
WHERE C.CustID = P.PurchCustID AND CL.LCTCustID = C.CustID 
GROUP BY C.CustQuality, CL.CLocation; 

SELECT C.CustQuality, CL.CLocation, COUNT(DISTINCT c.CustID) AS tot_Customer, COUNT(PurchID) AS tot_Purch 
FROM CustomerTable AS C, PurchaseTable AS P, CustomerLocation AS CL 
WHERE C.CustID = P.PurchCustID AND CL.LCTCustID = C.CustID AND CL.CLocation='North' 
GROUP BY C.CustQuality; 

Answer 2

這應該回答你的第一個問題

SELECT COUNT(DISTINCT c.CustID), CustQuality, COUNT(PurchID) FROM CustomerTable c 
INNER JOIN PurchaseTable p ON c.CustID = p.CustID 
GROUP BY CustQuality