leetcode练习题-mysql:185. 部门工资前三高的员工_mysql语句练习题部门薪水-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_34763130/article/details/88727485

博客介绍了一种数据处理思路，先对子表薪水进行去重，接着将薪水与子表对比，筛选出薪水高的数据并统计数量，最后为美观对部门和薪水做降序排序。

Employee 表包含所有员工信息，每个员工有其对应的 Id, salary 和 department Id 。

+----+-------+--------+--------------+
| Id | Name  | Salary | DepartmentId |
+----+-------+--------+--------------+
| 1  | Joe   | 70000  | 1            |
| 2  | Henry | 80000  | 2            |
| 3  | Sam   | 60000  | 2            |
| 4  | Max   | 90000  | 1            |
| 5  | Janet | 69000  | 1            |
| 6  | Randy | 85000  | 1            |
+----+-------+--------+--------------+
Department 表包含公司所有部门的信息。

+----+----------+
| Id | Name     |
+----+----------+
| 1  | IT       |
| 2  | Sales    |
+----+----------+
编写一个 SQL 查询，找出每个部门工资前三高的员工。例如，根据上述给定的表格，查询结果应返回：

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

Select d.Name as Department, e.Name as Employee, e.Salary 
from Department d, Employee e 
where e.DepartmentId = d.Id and (
    Select count(distinct Salary) From Employee where DepartmentId=d.Id and Salary > e.Salary
)< 3
order by Department ,Salary

思路: 先对子表薪水去重，然后将薪水与子表做对比，将薪水高的筛选出来，然后取数量
为了美观作了部门与薪水的降序排序