SQL Select 行，最大值在一列

Question

我有以下查询

SELECT Dnumber, SUM(WORKS_ON.Hours) AS sum_hours 
FROM DEPARTMENT 
JOIN PROJECT ON DEPARTMENT.Dnumber = PROJECT.Dnum 
JOIN WORKS_ON ON PROJECT.Pnumber = WORKS_ON.Pno 
GROUP BY Dnumber

结果：

Dnumber   sum_hours
--------------------
1           25.0
4          115.0
5          150.0

我想 select 与 MAX sum_hours的行。 我尝试使用

SELECT s.Dnumber, MAX(s.sum_hours)
FROM 
    (SELECT Dnumber, SUM(WORKS_ON.Hours) sum_hours 
     FROM DEPARTMENT 
     JOIN PROJECT ON DEPARTMENT.Dnumber = PROJECT.Dnum 
     JOIN WORKS_ON ON PROJECT.Pnumber = WORKS_ON.Pno 
     GROUP BY Dnumber) s 
GROUP BY s.Dnumber

但这会返回完全相同的结果（所有三行）。

知道如何实现这一目标吗？

Answer 1

尝试这个

SELECT TOP 1 Dnumber, SUM(WORKS_ON.Hours) sum_hours 
FROM DEPARTMENT 
JOIN PROJECT ON DEPARTMENT.Dnumber = PROJECT.Dnum 
JOIN WORKS_ON ON PROJECT.Pnumber = WORKS_ON.Pno GROUP BY Dnumber
ORDER BY SUM(WORKS_ON.Hours) DESC