All employees with the top three highest salaries in the Leecode department

Original title

EmployeeThe following table contains information about all employees, each employee has its corresponding job number Id, name Name, salary Salaryand department number DepartmentId.

+----+-------+--------+--------------+
| Id | Name  | Salary | DepartmentId |
+----+-------+--------+--------------+
| 1  | Joe   | 85000  | 1            |
| 2  | Henry | 80000  | 2            |
| 3  | Sam   | 60000  | 2            |
| 4  | Max   | 90000  | 1            |
| 5  | Janet | 69000  | 1            |
| 6  | Randy | 85000  | 1            |
| 7  | Will  | 70000  | 1            |
+----+-------+--------+--------------+

Department The table contains information about all departments of the company.

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

Write a SQL query to find all the employees in each department who received the top three highest salaries. For example, according to the table given above, the query result should return:

+------------+----------+--------+
| Department | Employee | Salary |
+------------+----------+--------+
| IT         | Max      | 90000  |
| IT         | Randy    | 85000  |
| IT         | Joe      | 85000  |
| IT         | Will     | 70000  |
| Sales      | Henry    | 80000  |
| Sales      | Sam      | 60000  |
+------------+----------+--------+

Explanation:

In the IT department, Max received the highest salary, Randy and Joe both received the second highest salary, and Will's salary ranked third. The sales department (Sales) has only two employees, Henry has the highest salary, and Sam has the second highest salary.

Source: LeetCode
Link: https://leetcode-cn.com/problems/department-top-three-salaries
Copyright is owned by LeetCode . For commercial reprints, please contact the official authorization. For non-commercial reprints, please indicate the source.

Solution 1

The top 3 salaries in the company means that there are no more than 3 salaries greater than these values.

select e1.Name as 'Employee', e1.Salary
from Employee e1
where 3 >
(
    select count(distinct e2.Salary)
    from Employee e2
    where e2.Salary > e1.Salary
)
;

In this code, we have counted how many people have higher salaries than e1.Salary, so the output of the sample should be as follows.

| Employee | Salary |
|----------|--------|
| Henry    | 80000  |
| Max      | 90000  |
| Randy    | 85000  |

Then, we need to join the Employee table and the Department table to obtain department information.

SELECT
    d.Name AS 'Department', e1.Name AS 'Employee', e1.Salary
FROM
    Employee e1
        JOIN
    Department d ON e1.DepartmentId = d.Id
WHERE
    3 > (SELECT
            COUNT(DISTINCT e2.Salary)
        FROM
            Employee e2
        WHERE
            e2.Salary > e1.Salary
                AND e1.DepartmentId = e2.DepartmentId
        )
;

| Department | Employee | Salary |
|------------|----------|--------|
| IT         | Joe      | 70000  |
| Sales      | Henry    | 80000  |
| Sales      | Sam      | 60000  |
| IT         | Max      | 90000  |
| IT         | Randy    | 85000  |