SQL计数通过分组加入

Question

我已经搜索了所有的SQL问题，并且我发现了我不想要的每个版本 - 所以我需要问一下。我处在一个大脑锁定中 - 知道有一个数字，数字和组合，以及所有连接在一起。

2表

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

我我试图计算过去30天内好，坏，新客户的购买次数。

我曾尝试加入和组数等，我不断收到：

• 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

我只是想整体效果

• 3信誉良好的客户取得6次购买
• 2个不良客户的数据制作6次购买
• 2新客户提出了5个Purcahses

然后为额外的功能...我有第三张表，我需要加入以及。 CustomerLocation

所以（CLID，CLLocation（北，南，东，西）的值），如果我想了解以下断裂组下来

• 3信誉良好的客户取得6个采购 - 1个客户是北，2个客户提供从南
• 2个不良客户的数据做6名购买 - 从东5客户，1西
• 2新客户取得5个Purcahses - 南
2客户

而且最后一个新的查询将... 哪里CLLocation =南

或者，如果我想按地区查找...

• 1信誉良好的客户取得3个购买
• 2不良客户的数据做2个购买
• 0新客户取得0 Purcahses

我知道我问了很多 - 但是，任何及所有的帮助将非常感谢！

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

这应该回答你的第一个问题

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