Employee table contains information on all employees, each has its corresponding employee Id, salary and department Id.
---- + -------- + ------- + + -------------- +
| Id | the Name | the 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 table contains information about all sectors of the company.
+ ---------- + ---- +
| Id | the Name |
+ ---- + ---------- +
| 1 | IT |
| 2 | Sales |
+ ---- + ---------- +
write a SQL query to find the top three high-wage employees of each department. For example, given the above table, the query results should be returned:
+------------+----------+--------+
| Department | Employee | Salary |
+------------+----------+--------+
| IT | Max | 90000 |
| IT | Randy | 85000 |
| IT | Joe | 70000 |
| Sales | Henry | 80000 |
| Sales | Sam | 60000 |
+------------+----------+--------+
Sql如下：
SELECT
d.Name Department,e1.Name Employee,e1.Salary Salary
FROM
Employee e1,
Employee e2 ,
Department d
WHERE
e1.DepartmentId = e2.DepartmentId
AND e1.Salary <= e2.Salary
and e1.DepartmentId=d.Id
group by e1.id
having count(DISTINCT e2.Salary)<=3
order by d.Name,e1.Salary desc