SQL查询与平均值和长度有关

Question

我有一个问题。即时通讯正在进行任务，并在一个特定请求中遇到问题。 请求是：

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

我已经得到了1 - 3，但我对4号做不了多少。 产品上的值可以有多个值，以逗号分隔。

〜＆GT; （产品编号：12,4,5） - ＆gt;如果订单购买超过1个产品

我到了可以将它与长度替换分开的地步，但我对如何将其显示为平均篮子大小感到困惑。

感谢您的帮助！

SQL表格图像 sql table

**Customer**
Customer ID
Name
AddressCity

**Order**
OrderID
CustomerID
ProductID
Total

**Delivery**
DeliveryID
OrderID
AddressCity

这是我当前的sql语句

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

应该为您提供每个订单的总产品数量。 只需将其添加到现有语句中即可。

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

修改
SELECT部分​​中使用的字段也应在GROUP BY部分中指定。您的查询将变为如此：

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