如何在两个表中找到平均工资最高的部门名称

Question

有两张桌子

Employee
Id
Name
Salary
DepartmentId

和

Departament
Id
Name

如何才能得到两张表中最高的平均工资 喜欢

Joe and Max belong to dept 1 so, avg is (70K+90K)/2
= 80K

和

Henry and Sam belog to dept 2, avg is (80K + 60K)/2=70k

那么如何通过部门选择最高的平均工资？，在这种情况下

IT 80K

我一直在尝试：

'按部门对工资进行分组，用Max函数取最高的。

select 
    Department.Name as Department,
    T.M as Salary
from
    Employee,
    Department,
    (select DepartmentId as ID, Max(Salary) as M from Employee group by DepartmentId) as T
where
    Employee.Salary = T.M and
    Department.Id = T.ID and 
    Employee.DepartmentId = Department.Id

enter image description here

Answer 1

如果多个部门的最高平均工资相同，则此解决方案将返回多行。

SELECT *
FROM(
SELECT d.Id, d.Name, AVG(e.Salary) avg_salary, RANK() OVER(ORDER BY AVG(e.Salary) DESC) AS rank_
FROM Employee e
INNER JOIN Departament d ON e.DepartmentId = d.Id
GROUP BY d.Id, d.Name
)T
WHERE rank_ = 1

Answer 2

如果您想获得部门的平均值，您可以使用这种方式。

select DepartmentId as ID,  de.name as Deptname,  Avg(Salary) as M from Employee em1 
       join Department de on de.departmentID = em1.DepartmentId 
          group by DepartmentId, de.name

如果您想要员工姓名和最高平均值，那么您也可以使用这种方法。

select 
Deptname as Department,
e.Name as Employeename, 
z.M as Salary
from
Employee e 
join 
( select DepartmentId,Deptname, M, row_number() (order by m desc) rownum from (   select DepartmentId as ID,  de.name as Deptname,  Avg(Salary) as M from Employee em1 
       join Department de on de.departmentID = em1.DepartmentId 
          group by DepartmentId, de.name) as T) z
on 
e.DepartmentId = T.DepartmentId  and z.rownum = 1 

Answer 3

如果您想要一个完整的答案，您应该提供 DDL、示例数据和所需的结果。 如果我理解正确，您正在寻找类似的东西：

SELECT DepartmentID, AVG(Salary) AS AverageSalaryForDept
FROM Employee
GROUP BY DepartmentID
ORDER BY AverageSalaryForDept DESC;

这将为您提供所有平均值，从最高到最低排序。现在如果你只想要最上面的，添加一个 FETCH 子句：

SELECT DepartmentID, AVG(Salary) AS AverageSalaryForDept
FROM Employee
GROUP BY DepartmentID
ORDER BY AverageSalaryForDept DESC
OFFSET 0 ROWS FETCH NEXT 1 ROW ONLY;

HTH