如何在sql中找到客户分类中的最大产品id？

Question

在这里，我有客户id和最大订单量，如何获得最大订单量的productid列以及customerid和maxorderqty列。

数据库:冒险工程

使用的表:salesorerheader、salesorderdetails

SELECT customerid,
       Max(totalqty)
FROM   (SELECT customerid,
               Sum(orderqty) AS Totalqty,
               productid     AS pdtid
        FROM   sales.salesorderheader a
               INNER JOIN sales.salesorderdetail b
                       ON a.salesorderid = b.salesorderid
        GROUP  BY customerid,
                  productid)A
WHERE  customerid = 29825
GROUP  BY customerid

Answer 1

如果您对查找单个记录感兴趣，可以使用以下内容：

SELECT TOP(1) CustomerID, max(totalqty) AS maxqty, pdtid
FROM
(
  SELECT customerid, Sum(orderqty) AS Totalqty, productid AS pdtid
  FROM   sales.salesorderheader a
    INNER JOIN sales.salesorderdetail b
      ON a.salesorderid = b.salesorderid
  GROUP  BY customerid, productid
) A
WHERE CustomerID=29825
GROUP BY CustomerID, pdtid
ORDER BY max(totalqty) DESC

但是..。如果要查找几个级别相同的记录，请使用以下命令：

SELECT *
FROM 
(
  SELECT RANK() OVER(ORDER BY max(totalqty) DESC) rnk, CustomerID, max(totalqty) AS maxqty, pdtid
  FROM
  (
    SELECT customerid, Sum(orderqty) AS Totalqty, productid AS pdtid
    FROM   sales.salesorderheader a
      INNER JOIN sales.salesorderdetail b
        ON a.salesorderid = b.salesorderid
    GROUP  BY customerid, productid
  ) A
  WHERE CustomerID=29825
  GROUP BY CustomerID, pdtid
) B
WHERE rnk = 1

db<>fiddle

另一种方法是再次“加入”sailes细节;)