In this Leetcode Department Highest Salary problem solution, The Employee table holds all employees. Every employee has an Id, a salary, and there is also a column for the department Id. The Department table holds all departments of the company.

Write a SQL query to find employees who have the highest salary in each of the departments. For the above tables, your SQL query should return the following rows (order of rows does not matter).

+------------+----------+--------+

| Department | Employee | Salary |

+------------+----------+--------+

| IT         | Max      | 90000  |

| IT         | Jim      | 90000  |

| Sales      | Henry    | 80000  |

+------------+----------+--------+

Leetcode Department Highest Salary problem solution


Problem solution in Oracle.

select d.Name as Department, e.NAME as Employee, e.SALARY as Salary  from Employee e 
inner join Department d
on e.DepartmentId=d.Id
inner join
(
select   
DepartmentId ,
max(Salary) as Salary
from Employee 
group by  DepartmentId
) a
on e.Salary=a.Salary and e.DepartmentId=a.DepartmentId



Problem solution in Mysql.

SELECT d.Department, e.Name as Employee, e.Salary
FROM (
    SELECT d.Name AS Department, d.Id AS dId, MAX(e.Salary) AS Salary
    FROM Employee e
    LEFT JOIN Department d
    ON e.DepartmentID = d.Id
    GROUP BY Department, dId
    ) d
INNER JOIN Employee e
ON d.Salary = e.Salary
AND d.dId = e.DepartmentId


Problem solution in C++.

select c.Name as Department, a.Name as Employee, a.Salary as Salary from (
select * from Employee
) a
inner join (
select max(Salary) as Salary, DepartmentId from Employee group by DepartmentId
) b on a.Salary = b.Salary and a.DepartmentId = b.DepartmentId
left join (
select * from Department
) c on a.DepartmentId = c.Id where c.Name is not null