SQL Count Inner Join by Grouping

Question

我搜索了所有的SQL问题，我找到了我不想要的每个版本 - 所以我需要问一下。我处于大脑锁定状态 - 知道有一个计数，总和，小组和一个联合都被扔在一起。

2桌

1. CustomerTable - CustID，CustQuality（价值观是好客户，坏客户，新客户等）
2. PurchaseTable（PurchID，PurchItem，PurchDate）

我正在尝试计算过去30天内Good，Bad，New Customers的购买量。

我已尝试过加入和小组计数等，我一直在接受：

• 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。

我只想要整体结果

• 3位好客户进行了6次购买
• 2个坏客户进行了6次购买
• 2位新客户制作了5个Purcahses

然后为了额外的功能......我还有第三张桌子，我也需要加入。 CustomerLocation（CLID，CLLocation（北，南，东，西）的值）

所以，如果我想知道以下细分群体

• 3位好客户进行了6次购买 - 1位客户来自北方，2位来自南方的客户
• 2个坏客户进行了6次购买 - 来自East的5位客户，1位West
• 2位新客户制作了5个Purcahses - 来自South的2位客户

最后一个新查询将是...... WHERE CLLocation = South

或者，如果我想按区域查找......

• 1好客户进行了3次购买
• 2个坏客户进行了2次购买
• 0新客户提出0 Purcahses

我知道我要求很多 - 但是任何和所有帮助都会受到极大的赞赏！

Answer 1

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

Answer 2

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;