MySQL：从内联子查询返回多个列

Question

我正在创建一个SQL语句，它将逐月返回销售摘要。

摘要将列出日期，销售总数和销售总价值的一些简单列。

但是，除了这些专栏之外，我还想再增加3个专栏，根据花费的数量列出月份最佳客户。 对于这些列，我需要某种内联子查询，可以返回他们的ID，名称和他们花费的金额。

我当前的努力使用内联SELECT语句，但是，根据我对如何实现这些语句的了解，每个内联语句只能返回一列和一行。

为了解决这个问题，我当然可以创建3个单独的内联语句，但是，除了这个看似不切实际的内容之外，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建此查询？

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全面的回答

经过对Dave Barkers解决方案的一些调整后，我有一个最终版本供将来寻求帮助的人使用。

Dave Barker的解决方案与客户详细信息完美配合，但是，它使得总销售额和总销售额数列更加简单。

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

Answer 1

将内联SQL移动为内部联接查询。 所以你有类似......

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

Answer 2

试一试：

  SELECT CONCAT(o.order_month, ' ', o.order_year),
         o.total_orders,
         o.total_amount,
         x.sum_order_total,
         x.ordercustomerfk,
         x.customername
    FROM (SELECT MONTH(t.orderdate) AS order_month,
                 YEAR(t.orderdate) AS order_year
                 COUNT(t.orderid) AS total_orders, 
                 SUM(t.ordertotal) AS total_amount
            FROM ORDERS t
        GROUP BY MONTH(t.orderdate), YEAR(t.orderdate)) o
    JOIN (SELECT MONTH(t.orderdate) AS ordermonth,
                 YEAR(t.orderdate) AS orderyear
                 SUM(t.ordertotal) 'sum_order_total',
                 t.ordercustomerfk,
                 c.customername
            FROM ORDERS t
            JOIN CUSTOMERS c ON c.customerid = o.ordercustomerfk
        GROUP BY t.ordercustomerfk, MONTH(t.orderdate), YEAR(t.orderdate)) x ON x.order_month = o.order_month
                                                                            AND x.order_year = o.order_year
ORDER BY o.order_year DESC, o.order_month DESC

Answer 3

你也可以这样做：

SELECT 
    a.`y`,
    ( SELECT @c:=NULL ) AS `temp`,
    ( SELECT @d:=NULL ) AS `temp`,
    ( SELECT 
          CONCAT(@c:=b.`c`, @d:=b.`d`) 
      FROM `b`
      ORDER BY b.`uid` 
      LIMIT 1 ) AS `temp`,
    @c as c,
    @d as d
 FROM `a`