如何修复 Group By 中的聚合，缺少聚合值答案

【问题标题】：How to fix Aggregation in Group By, missing aggregation values如何修复 Group By 中的聚合，缺少聚合值
【发布时间】：2019-12-10 18:07:12
【问题描述】：

我有一张销售信息表，并且对按客户分组以及返回几列的总和、计数、最大值感兴趣。请有任何想法。

我检查了 Group By 语句中包含的所有 Select 列，返回的不是分组和聚合值的详细信息。
我尝试了一些明确的命名，但没有帮助。

SELECT
    customerID AS CUST,
    COUNT([InvoiceID]) AS Count_Invoice,
    SUM([Income]) AS Total_Income,
    SUM([inc2015]) AS Tot_2015_Income,
    SUM([inc2016]) AS Tot_2016_Income,
    MAX([prodA]) AS prod_A,
FROM [table_a] 
GROUP BY
    customerID, InvoiceID,Income,inc2015, inc2016, prodA

CUST 有多行，即 CUST 1、2 等应该有一行......它应该这样说......

    ---------------------------------------------
    CUST    Count_Invoice   Total_Income    Tot_2015_Income Tot_2016_Income prod_A

       1    2   600 300 300 2


    BUT IT IS RETURNING THIS
    ======================================
    CUST    Count_Invoice   Total_Income    Tot_2015_Income Tot_2016_Income prod_A

       1    1   300 300 0   1

       1    1   300 0   300 1

       2    1   300 0   300 1

       2    1   500 0   500 0

       3    2   800 0   800 0

       3    1   300 0   300 1

【问题讨论】：

标签： sql-server group-by grouping aggregation

【解决方案1】：

根据您预期输出的描述，您应该仅按客户进行汇总：

SELECT
    customerID A CUST,
    COUNT([InvoiceID]) AS Count_Invoice,
    SUM([Income]) AS Total_Income,
    SUM([inc2015]) AS Tot_2015_Income,
    SUM([inc2016]) AS Tot_2016_Income,
    MAX([prodA]) AS prod_A
FROM [table_a] 
GROUP BY  
    customerID;

【讨论】：

谢谢，我误解了需要镜像groupby/select items

【解决方案2】：

您不需要group by 其他列，因为它们已经由count、min、max 或sum 聚合。

所以你可以试试这个

SELECT customerID as CUST
,count([InvoiceID]) as Count_Invoice
 ,sum([Income]) as Total_Income
,sum([inc2015]) as Tot_2015_Income
 ,sum([inc2016]) as Tot_2016_Income
,max([prodA])  as prod_A    --- here you are taking Max but in output it seems like sum
 FROM [table_a] 
 Group By customerID

注意：对于列prod_A，您使用的是max，它给出了1，但结果显示2，实际上是sum 或count。请检查。

有关更多信息，您可以找到Group by 的链接。

【讨论】：