Department Highest Salary

The Employee table holds all employees. Every employee has an Id, a salary, and there is also a column for the department Id.

+----+-------+--------+--------------+ | Id | Name | Salary | DepartmentId | +----+-------+--------+--------------+ | 1 | Joe | 70000 | 1 | | 2 | Henry | 80000 | 2 | | 3 | Sam | 60000 | 2 | | 4 | Max | 90000 | 1 | +----+-------+--------+--------------+

The Department table holds all departments of the company.

+----+----------+ | Id | Name | +----+----------+ | 1 | IT | | 2 | Sales | +----+----------+

Write a SQL query to find employees who have the highest salary in each of the departments. For the above tables, Max has the highest salary in the IT department and Henry has the highest salary in the Sales department.

+------------+----------+--------+ | Department | Employee | Salary | +------------+----------+--------+ | IT | Max | 90000 | | Sales | Henry | 80000 | +------------+----------+--------+

Solution

select d1.Name as Department, e1.Name as Employee, e1.Salary as Salary
from Employee e1, Department d1, 

(select d.Id as Id, e.Name as Employee, max(e.Salary) as Salary
from Employee e, Department d
where e.DepartmentId = d.Id
group by d.Id) as a

where e1.DepartmentId = d1.Id and d1.Id = a.Id and a.Salary = e1.Salary