185. 部门工资前三高的所有员工

185. 部门工资前三高的所有员工

# Write your MySQL query statement below
select d.name Department, e1.Name Employee, e1.Salary from Employee e1 left join Employee e2 
    on e1.DepartmentId = e2.DepartmentId and e1.Salary < e2.Salary
    join Department d on e1.DepartmentId = d.Id 
    group by e1.Id having count(distinct e2.Salary) <=2 order by e1.Salary desc;

首先使用左连接，进行第一次筛选，选出比当前的工资高的数据

然后再和department进行inner join一次，删除不合法的数据

然后再就是调用group by，进行分组以便于查询

然后分组之后，判断个数即可，如果大于当前值的不重复的有两个，就算符合规则