LeetCode 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  |
+------------+----------+--------+

select p.department as Department, 
e2.name as Employee, 
p.salary from (
    select d.name as department, 
    d.id as departmentid,
    max(e1.salary) as salary 
    from Employee e1, Department d 
    where e1.departmentid = d.id 
    group by d.name, d.id
) as p, Employee e2 
where e2.departmentid = p.departmentid and e2.salary = p.salary;

LeetCode Department Highest Salary

原文：http://blog.csdn.net/u012925008/article/details/45010311