如何获得一个组的最小值？

Posted 2023-03-16

【中文标题】如何获得一个组的最小值？

【英文标题】：How to get minimum value of a group?

【发布时间】：2020-01-27 18:05:13

【问题描述】：

我需要获取每个项目（PrjCode）的最小 lineTotal 的报价注释。如何得到它 以下查询我已经尝试过，但没有奏效

  select distinct a.PrjCode,b.LineTotal as 'Neg.rate',(case when min(b.LineTotal) = b.LineTotal then c.Comments end)
from OPRJ a
Left Join PQT1 b on b.Project = a.PrjCode
Inner Join OPQT c on c.DocEntry = b.DocEntry
Group by a.PrjCode,a.PrjName,b.LineTotal,c.Comments
having min(b.LineTotal) = b.LineTotal
Order by a.PrjCode

输出如下

预期输出如下

【问题讨论】：

编辑您的问题并显示示例数据以及所需的结果。某种 db fiddle 也很有帮助。

【参考方案1】：

当您使用 group by 时，您不需要使用 distinct，尽管没有可用的示例数据，只是假设下面可能对您有用

select  a.PrjCode,b.LineTotal as 'Neg.rate',
min(c.Comments )
from OPRJ a
Left Join PQT1 b on b.Project = a.PrjCode
Inner Join OPQT c on c.DocEntry = b.DocEntry
Group by a.PrjCode,a.PrjName,b.LineTotal    
Order by a.PrjCode

【参考方案2】：

试试这个查询

     SELECT c.PrjCode, b.LineTotal AS 'Neg.rate', e.Comments FROM ( 
     (SELECT a.PrjCode, MIN(b.LineTotal) AS LineTotal FROM OPRJ a
     LEFT JOIN PQT1 b ON b.Project = a.PrjCode GROUP BY a.PrjCode)c
     INNER JOIN  PQT1 d ON d.Project = c.PrjCode AND d.LineTotal = c.LineTotal
     INNER JOIN  OPQT e ON e.DocEntry = d.DocEntry ORDER BY c.PrjCode)f;

【参考方案3】：

试试这个

select  a.PrjCode,b.LineTotal as 'Neg.rate', c.Comments
from OPRJ a
Left Join PQT1 b on b.Project = a.PrjCode
Inner Join OPQT c on c.DocEntry = b.DocEntry
Group by a.PrjCode
Order by b.LineTotal, a.PrjCode