Question

我有两个桌子。一个给员工

select
  avg(notificationcount) as statistic_mean,
  median(notificationcount) as statistic_median,
  stats_mode(notificationcount) as statistic_mode
from mytable;

一个代表部门名称

LAST_NAME                     SALARY DEPARTMENT_ID
------------------------- ---------- -------------
Vargas                          2500            50
Zlotkey                        10500            50
Abel                           11000            80
Taylor                          8600            80

我想在employees表中选择薪水最高的前三名雇员，得到后我想获得他们的部门名。这样的结果。

DEPARTMENT_ID DEPARTMENT_NAME               
------------- ------------------------------
50            Shipping
80            Sales

我尝试过：

LAST_NAME                     SALARY DEPARTMENT_NAME
------------------------- ---------- -------------
Abel                          11000       Sales
Zlotkey                       10500       Shipping
Taylor                         8600       Sales

但是我不知道如何使用join来获取department_name。

平台：Windows10

SQLDeveloper版本：18.01

Answer 1

您可以对子查询执行JOIN：

SELECT e.LAST_NAME, e.SALARY, d.DEPARTMENT_NAME
FROM employees e INNER JOIN
     department d
     ON d.DEPARTMENT_ID = e.DEPARTMENT_ID
WHERE e.DEPARTMENT_ID = (SELECT e1.DEPARTMENT_ID
                         FROM employees e1
                         ORDER BY e1.SALARY DESC
                         FETCH FIRST 1 ROWS ONLY
                        );

编辑：如果只需要三名员工，则可以：

SELECT e.LAST_NAME, e.SALARY, d.DEPARTMENT_NAME
FROM employees e INNER JOIN
     department d
     ON d.DEPARTMENT_ID = e.DEPARTMENT_ID
ORDER BY e.SALARY DESC
FETCH FIRST 3 ROWS ONLY

Answer 2

尝试

select top(3)LAST_NAME, SALARY, DEPARTMENT_NAME 
from employees e
inner join  department  d on e.DEPARTMENT_ID = d.DEPARTMENT_ID
where d.DEPARTMENT_NAME = 'sales'
order by SALARY desc

Answer 3

您可以使用窗口功能来做到这一点：

select e.last_name, e.salary, d.department_name
from (select e.*, max(sum_salary) over () as max_sum_salary

      from (select e.*, sum(e.salary) over (partition by department_id) as sum_salary
            from employees e
            ) e
     ) e join
     department d
     on e.department_id = d.department_id
where max_sum_salary = sum_salary

合并top并加入sql

3 个答案: