Question

我为Oracle做了这个任务。它要求我显示部门名称（部门是包含该表的manager_id，department_id和department_name的表），该部门的manager_id，经理的名称（在employees表中找到）以及该部门的平均工资（每个员工的工资也在员工中找到）。一旦我尝试检索经理名称（我想通过将他在部门中的ID与员工中的ID进行比较）就会弄乱我的平均值。没有它（如下），它可以正常工作

SELECT d.department_name, AVG(e.salary) as "Salaries"
FROM   employees e join departments d on e.department_id=d.department_id
WHERE  d.manager_id=e.employee_id
GROUP BY e.department_id, d.department_name,d.manager_id
ORDER BY AVG(e.salary)

有人可以帮我解决这个问题吗？或许可以解释为什么我搞砸了？

Answer 1

在查询中选择管理员名称中引入相关子查询。

SELECT d.department_name,
       AVG(e.salary) AS "Salaries",
       (SELECT first_name
               ||' '
               ||last_name
        FROM   employees i
        WHERE  i.employee_id = d.manager_id) AS manager_name
FROM   employees e
       join departments d
         ON e.department_id = d.department_id
GROUP  BY e.department_id,
          d.department_name,
          d.manager_id
ORDER  BY Avg(e.salary);

Answer 2

WITH factoring clause选择平均工资;然后将它连接到其他表

RewriteEngine on
RewriteCond %{HTTP_HOST} ^example.com [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301,NC]

快速检查2个部门：

SQL> with avgsal as
  2    (select e.department_id, round(avg(e.salary)) avg_sal
  3     from employees e
  4     group by e.department_id
  5    )
  6  select d.department_id,
  7         d.department_name,
  8         m.last_name manager,
  9         a.avg_sal
 10  from departments d
 11  join employees m on m.department_id = d.department_id
 12       and m.employee_id = d.manager_id
 13  join avgsal a on a.department_id = d.department_id
 14  order by a.avg_sal;

DEPARTMENT_ID DEPARTMENT_NAME      MANAGER                      AVG_SAL
------------- -------------------- ------------------------- ----------
           50 Shipping             Fripp                           3476
           30 Purchasing           Raphaely                        4150
           10 Administration       Whalen                          4400
           60 IT                   Hunold                          5760
           40 Human Resources      Mavris                          6500
          100 Finance              Greenberg                       8601
           80 Sales                Russell                         8956
           20 Marketing            Hartstein                       9500
           70 Public Relations     Baer                           10000
          110 Accounting           Higgins                        10154
           90 Executive            King                           19333

11 rows selected.

SQL>

聚合函数和连接2个条件

2 个答案: