SQL-使用条件选择每组前 3 个值

Question

我想针对每个标签的不同产品类别提取前 3 名最畅销的产品。 数据如下所示:

tag  | product_name | product_category | order_count
tag1 | product1     | category1        | 100
tag1 | product2     | category2        | 80
tag1 | product3     | category2        | 60
tag1 | product4     | category3        | 50
......

我知道如何使用 ROW_NUMBER() 提取每个标签的前 3 个畅销产品，但它将返回 Product1、product2、product3。我不想要product3，因为它与product2属于同一类别。我想要产品 4。如何在 SQL Server 中执行此操作？

Answer 1

第一个 ROW_NUMBER 删除每个标签和产品类别的重复行，第二个 ROW_NUMBER 选择每个标签最畅销的 3 个产品

;WITH cte AS
 (SELECT *, ROW_NUMBER() OVER(PARTITION BY tag, product_category ORDER BY order_count DESC) AS rn
  FROM yourtable
  ), cte2 AS
  (SELECT *, ROW_NUMBER() OVER(PARTITION BY tag ORDER BY order_count DESC) AS rn2
   FROM cte
   WHERE rn = 1
   )
   SELECT *
   FROM cte2
   WHERE rn2 <= 3

演示 SQLFiddle

下一个使用派生表

;WITH cte AS
 (SELECT t2.tag, t2.product_name, t2.product_category, t2.order_count,
         ROW_NUMBER() OVER(PARTITION BY t2.tag ORDER BY order_count DESC) AS rn
  FROM (SELECT tag, product_category, MAX(order_count) AS maxCount
        FROM yourtable
        GROUP BY tag, product_category
        ) t1 JOIN yourtable t2 ON t1.tag = t2.tag 
          AND t1.product_category = t2.product_category
          AND maxCount = order_count
  )
  SELECT *
  FROM cte
  WHERE rn <= 3

演示 SQLFiddle