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Accepted
Neal
Asked: 2017-05-06 07:43:55 +0800 CST

一列上的 DISTINCT 并返回 TOP 行

  • 772

您如何查询三个最大的唯一客户Purchase_Cost？

我想应用DISTINCTonly on Customer_Name，但下面的查询将 distinct 应用于所有三列。我应该如何修改查询以获得所需的输出？

SELECT DISTINCT TOP 3 customer_name, order_no, Purchase_Cost  
FROM PurchaseTable 
ORDER BY Purchase_Cost

在此处输入图像描述

sql-server distinct

3 个回答

  1. Best Answer

    在以下查询中替换您的 dbname 和 schemaName。

    ;WITH CTE AS 
(
SELECT  
       [Order_No]
      ,[Customer_Name]
      ,[Purchase_Cost]
     , ROW_NUMBER() OVER(PARTITION BY [customer Name] ORDER BY [Purchase Cost] DESC) AS "RowNumber"
  FROM [dbname].[schemaName].[PurchaseTable]
  )

  SELECT TOP(3)
       [Order_No]
      ,[Customer_Name]
      ,[Purchase_Cost]
  FROM CTE WHERE RowNumber=1
  ORDER BY [Purchase_Cost] DESC

    我相信还有其他方法可以做到这一点。我建议你阅读这个。

    • 9

  2. 请试试：

    SELECT DISTINCT TOP 3  order_no, customer_name,  Purchase_Cost
FROM
(   SELECT order_no, customer_name, Purchase_Cost, ROW_NUMBER() OVER(PARTITION BY customer_name ORDER BY Purchase_Cost DESC) Orders
    FROM PurchaseTable
) A
WHERE A.Orders = 1
ORDER BY Purchase_Cost DESC
    • 1

  3. 我认为这可能比其他解决方案更有效，前提是您有以下索引： (Customer_Name, Purchase_Cost DESC) INCLUDE (Order_No)

    ;
WITH PurchaseTable AS
(
    SELECT * 
      FROM (VALUES ((501),('Carson'),(3400)),
                   ((502),('Thomas'),(625)),
                   ((503),('Daisy'),(4856)),
                   ((504),('Mary'),(2397)),
                   ((505),('Carson'),(5000))
           ) AS T(Order_No,Customer_Name,Purchase_Cost)
),
DistinctCustomers AS
(
    SELECT DISTINCT
           Customer_Name
      FROM PurchaseTable
)
SELECT TOP(3) 
       MaxCustomerOrder.Order_No,
       dc.Customer_Name,
       MaxCustomerOrder.Purchase_Cost
  FROM DistinctCustomers dc
 CROSS APPLY (SELECT TOP(1) * 
                FROM PurchaseTable pt 
               WHERE pt.Customer_Name = dc.Customer_Name 
               ORDER BY pt.Purchase_Cost DESC
             )    AS MaxCustomerOrder
 ORDER BY MaxCustomerOrder.Purchase_Cost DESC
;

    或者没有内联表定义：

    ;
WITH DistinctCustomers AS
(
    SELECT DISTINCT
           Customer_Name
      FROM PurchaseTable
)
SELECT TOP(3) 
       MaxCustomerOrder.Order_No,
       dc.Customer_Name,
       MaxCustomerOrder.Purchase_Cost
  FROM DistinctCustomers dc
 CROSS APPLY (SELECT TOP(1) * 
                FROM PurchaseTable pt 
               WHERE pt.Customer_Name = dc.Customer_Name 
               ORDER BY pt.Purchase_Cost DESC
             )    AS MaxCustomerOrder
 ORDER BY MaxCustomerOrder.Purchase_Cost DESC
;
    • 0

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