我正在创建一个 SQL 语句，它将返回每月的销售摘要。

摘要将列出日期、销售总数和销售总值的一些简单列。

但是，除了这些列之外，我还想再添加 3 个列，这些列将按花费的金额列出最佳客户的月份。对于这些列，我需要某种内联子查询，可以返回它们的 ID、名称和花费的金额。

我目前的工作是使用内联 SELECT 语句，但是，根据我对如何实现这些的了解，每个内联语句只能返回一列和一行。

为了在我的场景中解决这个问题，我当然可以创建 3 个单独的内联语句，但是，除了这看起来不切实际之外，它还会增加查询时间。

SELECT  
    DATE_FORMAT(OrderDate,'%M %Y') AS OrderMonth,
    COUNT(OrderID) AS TotalOrders, 
    SUM(OrderTotal) AS TotalAmount, 

    (SELECT SUM(OrderTotal) FROM Orders WHERE DATE_FORMAT(OrderDate,'%M %Y') = OrderMonth GROUP BY OrderCustomerFK ORDER BY SUM(OrderTotal) DESC LIMIT 1) AS TotalCustomerAmount,

    (SELECT OrderCustomerFK FROM Orders WHERE DATE_FORMAT(OrderDate,'%M %Y') = OrderMonth GROUP BY OrderCustomerFK ORDER BY SUM(OrderTotal) DESC LIMIT 1) AS CustomerID,

    (SELECT CustomerName FROM Orders INNER JOIN Customers ON OrderCustomerFK = CustomerID WHERE DATE_FORMAT(OrderDate,'%M %Y') = OrderMonth GROUP BY OrderCustomerFK ORDER BY SUM(OrderTotal) DESC LIMIT 1) AS CustomerName

FROM Orders     
GROUP BY DATE_FORMAT(OrderDate,'%m%y')
ORDER BY DATE_FORMAT(OrderDate,'%y%m') DESC

我怎样才能更好地构造这个查询？

完整答案

在对 Dave Barkers 解决方案进行了一些调整后，我为将来寻求帮助的任何人提供了最终版本。

Dave Barker 的解决方案与客户详细信息完美配合，但是，它使更简单的 Total Sales 和 Total Sale Amount 列得到了一些疯狂的数字。

SELECT  
        Y.OrderMonth,   Y.TotalOrders,  Y.TotalAmount,
        Z.OrdCustFK,  Z.CustCompany,    Z.CustOrdTotal, Z.CustSalesTotal   


 FROM 
        (SELECT
            OrdDate,
            DATE_FORMAT(OrdDate,'%M %Y') AS OrderMonth, 
            COUNT(OrderID) AS TotalOrders, 
            SUM(OrdGrandTotal) AS TotalAmount
            FROM Orders
            WHERE OrdConfirmed = 1    
            GROUP BY DATE_FORMAT(OrdDate,'%m%y') 
            ORDER BY DATE_FORMAT(OrdDate,'%Y%m') DESC)
    Y INNER JOIN 
        (SELECT 
            DATE_FORMAT(OrdDate,'%M %Y') AS CustMonth, 
            OrdCustFK, 
            CustCompany, 
            COUNT(OrderID) AS CustOrdTotal,
            SUM(OrdGrandTotal) AS CustSalesTotal 
        FROM Orders INNER JOIN CustomerDetails ON OrdCustFK = CustomerID
        WHERE OrdConfirmed = 1
        GROUP BY DATE_FORMAT(OrdDate,'%m%y'), OrdCustFK 
        ORDER BY SUM(OrdGrandTotal) DESC) 
    Z ON Z.CustMonth = Y.OrderMonth

GROUP BY DATE_FORMAT(OrdDate,'%Y%m')
ORDER BY DATE_FORMAT(OrdDate,'%Y%m') DESC

最佳答案

将内联 SQL 移动为内连接查询。所以你会有类似...

SELECT  DATE_FORMAT(OrderDate,'%M %Y') AS OrderMonth, COUNT(OrderID) AS TotalOrders, SUM(OrderTotal) AS TotalAmount,  Z.OrderCustomerFK, Z.CustomerName, z.OrderTotal as CustomerTotal   
  FROM Orders     
  INNER JOIN (SELECT DATE_FORMAT(OrderDate,'%M %Y') as Mon, OrderCustomerFK, CustomerName, SUM(OrderTotal) as OrderTotal 
                FROM Orders 
               GROUP BY  DATE_FORMAT(OrderDate,'%M %Y'), OrderCustomerFK, CustomerName ORDER BY SUM(OrderTotal) DESC LIMIT 1) Z
          ON Z.Mon = DATE_FORMAT(OrderDate,'%M %Y')
    GROUP BY DATE_FORMAT(OrderDate,'%m%y'), Z.OrderCustomerFK, Z.CustomerName
    ORDER BY DATE_FORMAT(OrderDate,'%y%m') DESC

关于sql - MySQL:从内联子查询返回多列，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/1760817/