获取具有最大总缺陷数量的缺陷类型答案

【问题标题】：Get the Defect Type with the maximum Total Defect Qty获取具有最大总缺陷数量的缺陷类型
【发布时间】：2021-03-19 05:56:22
【问题描述】：

我有以下查询，它获取每个缺陷类型的缺陷数量总和：

SELECT 
[Defect Type]
,YEAR([Date]) AS YearOfDefect
,SUM([Total Defect Qty]) AS [Sum] FROM SupplierQuality
GROUP BY [Defect Type],YEAR([Date])

这是结果：

我想要总缺陷数量之和最大的缺陷类型，如下所示：

DefectType  YearOfDefect Sum    
No Impact   2019         586780230
No Impact   2018         437989564

【问题讨论】：

我假设您在一年之后达到了最大SUM？如果不是，那是什么定义了您所拥有的 2 行，因为它们具有相同的缺陷类型。
说 2018 年 Rejected 比别人多，你要返回那一年的 Rejected 吗？

标签： sql sql-server tsql aggregate-functions greatest-n-per-group

【解决方案1】：

另请参考另一种方法：

with cte
as(SELECT 
[Defect Type]
,YEAR([Date]) AS YearOfDefect
,SUM([Total Defect Qty]) AS [Sum] FROM SupplierQuality
GROUP BY [Defect Type],YEAR([Date]))
,cte2 as
(select YearOfDefect,max([Sum]) [Sum] 
from cte 
group by YearOfDefect)

select c1.[Defect Type],c2.YearOfDefect,c2.[Sum] 
from cte c1
join c2
on c1.[Defect Type]=c2.[Defect Type] and c1.YearOfDefect=c2.YearOfDefect

【讨论】：

【解决方案2】：

假设我在 cmets 中所做的假设是每年，那么您可以使用 ROW_NUMBER 来获取每组的“顶部”行：

WITH CTE AS(
    SELECT [Defect Type],
           YEAR([Date]) AS YearOfDefect,
           SUM([Total Defect Qty]) AS [Sum]
    FROM SupplierQuality
    GROUP BY [Defect Type],
             YEAR([Date]))
SELECT TOP (1) WITH TIES
       [Defect Type],
       YearOfDefect,
       [Sum]
FROM CTE
ORDER BY ROW_NUMBER() OVER (PARTITION BY YearOfDefect ORDER BY [Sum] DESC);

【讨论】：

【解决方案3】：

一个简单的选项使用with ties:

SELECT TOP (1) WITH TIES
    [Defect Type],
    YEAR([Date]) AS YearOfDefect,
    SUM([Total Defect Qty]) AS [Sum] 
FROM SupplierQuality
GROUP BY [Defect Type], YEAR([Date])
ORDER BY RANK() OVER(PARTITION BY YEAR([Date]) ORDER BY SUM([Total Defect Qty]) DESC)

缺点是这不能让您控制结果集的顺序。如果您确实需要该功能，请使用子查询：

SELECT *
FROM (
    SELECT
        [Defect Type],
        YEAR([Date]) AS YearOfDefect,
        SUM([Total Defect Qty]) AS [Sum],
         RANK() OVER(PARTITION BY YEAR([Date]) ORDER BY SUM([Total Defect Qty]) DESC) rn
    FROM SupplierQuality
    GROUP BY [Defect Type], YEAR([Date])
) t
WHERE rn = 1
ORDER BY YearOfDefect

【讨论】：