Question

员工属于部门（外键= D_ID）。员工拥有SSN（主键），姓名，薪水和D_ID。

一个部门有多名员工（主键= ID）

我想要一个查询，该查询返回部门名称|该部门最高薪雇员的姓名|他的薪水|在同一部门工作的员工的平均工资。

我知道如何选择第一部分：

SELECT 
    D.name, E.name, E.salary 
FROM 
    Employee E, Department D 
WHERE
    salary IN (SELECT MAX(E.salary) 
               FROM Employee E 
               GROUP BY E.D_ID)  
    AND E.D_ID = D.ID

我也知道如何选择最后一部分：

SELECT AVG(E.salary) 
FROM Employee E 
GROUP BY E.D_ID

如何在单个查询中将它们放在一起？

Answer 1

我会做这样的事情：

SELECT d.name
     , e.name
     , e.salary
     , n.avg_salary
  FROM Department d
  JOIN ( SELECT m.d_id
              , MAX(m.salary) AS max_salary
              , AVG(m.salary) AS avg_salary 
           FROM Employee m
          GROUP BY m.d_id
       ) n
    ON n.d_id = d.id

  JOIN Employee E
    ON e.d_id   = d.id
   AND e.salary = n.max_salary

Answer 2

您可以为此使用窗口功能：

select department_name, employee_name, salary, avg_dept_salary 
from (
  select e.name as employee_name, 
         d.name as department_name, 
         e.salary,
         max(e.salary) over (partition by d.id) as max_dept_salary, 
         avg(e.salary) over (partition by d.id) as avg_dept_salary
  from Employee E
    join Department D on e.d_id = d.id
) t 
where salary = max_dept_salary
order by department_name;

以上是标准的ANSI SQL，可以在所有现代DBMS上运行。

最高薪员工+各部门平均薪资

2 个答案: