有關SQL Query的平均值和長度

Question

我有一個問題。即時通訊正在做一項任務，並且在某個特定請求中遇到問題。 的要求是：

Find Customers who have purchased more than 2 times. Get the 
1. customer information 
2. purchase frequency 
3. total spending 
4. avg basket size. 

我已經有1 - 3，但我不能做很多有關數字4 產品的價值可以有多個值，以逗號分隔。

〜>（產品編號：12,4,5） - >如果訂單購買超過1產物

我得到其中i可以與長度分開它替換，但即時通訊有點糊塗上的點如何將其展示給平均籃子大小。

感謝您的任何幫助！

SQL表圖片 sql table

**Customer** 
Customer ID 
Name 
AddressCity 

**Order** 
OrderID 
CustomerID 
ProductID 
Total 

**Delivery** 
DeliveryID 
OrderID 
AddressCity 

這是我當前的SQL語句

SELECT Customer.*, Order.CustomerID, 
    COUNT(Order.CustomerID) AS PurchaseFrequency, 
    SUM(Order.Total) AS TotalSpending 
    FROM Customer JOIN Order 
    ON Customer.CustomerID=Order.CustomerID 
    Group By Customer.CustomerID 
    Having Count(*) > 1 

Answer 1

LEN(Order.ProductID) - LEN(REPLACE(Order.ProductID, ',', '')) + 1 

應該給你每個訂單的產品總量。 只需將其添加到您的現有聲明。

SELECT Customer.*, Order.CustomerID, 
    COUNT(Order.CustomerID) AS PurchaseFrequency, 
    SUM(Order.Total) AS TotalSpending, 
    AVG(LEN(Order.ProductID) - LEN(REPLACE(Order.ProductID, ',', '')) + 1) as AvgProdQuantityPerOrder 
    FROM Customer JOIN Order 
    ON Customer.CustomerID=Order.CustomerID 
    Group By Customer.CustomerID 
    Having Count(*) > 1 

編輯：
在SELECT部分​​中所使用的字段也應該在GROUP BY指定部分。然後，您的查詢就會變成這樣的事：

SELECT Customer.CustomerID, Customer.Name, Customer.AdressCity, 
     COUNT(Order.CustomerID) AS PurchaseFrequency, 
     SUM(Order.Total) AS TotalSpending, 
     AVG(LEN(Order.ProductID) - LEN(REPLACE(Order.ProductID, ',', '')) + 1) as AvgProdQuantityPerOrder 
FROM Customer JOIN 
     Order ON Customer.CustomerID=Order.CustomerID 
GROUP BY Customer.CustomerID, Customer.Name, Customer.AdressCity 
Having Count(*) > 1