MySQL两个表查询薪资特定排名的通用sql语句

最近刷了挺久的leetCode的sql题，总结了以下部分规律
可以解决LeetCode中的许多题目：

例如以下查询两个部门薪资的排名前二的薪水时多少
Employee 表

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

Department 表

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

查询结果

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

SELECT
    d.NAME AS 'Department',
    e1.NAME AS 'Employee',
    e1.Salary 
FROM
    Employee e1
    JOIN Department d ON e1.DepartmentId = d.Id 
WHERE
#比查询出来的Salary大的个数最多为2，则表示是前三
     (
SELECT
    COUNT( DISTINCT e2.Salary ) 
FROM
    Employee e2 
WHERE
    e2.Salary > e1.Salary 
    AND e1.DepartmentId = e2.DepartmentId 
    ) <3;

可以解决包括：

184题：部门薪资最高的员工（中等题）

185题. 部门工资前三高的所有员工（困难题）

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