Sql 我在执行下面的数据库查询时遇到问题

我在执行下面的数据库查询时遇到问题

我使用的是Oracle 11g企业版

问题1：

SELECT d.department_id, max(salary), min(salary), avg(salary), count(*) no_of_employees
FROM departments d, employees e
WHERE e.department_id = d.department_id
GROUP BY d.department_id

结果：输出成功

问题2：

SELECT d.department_id, d.department_name, max(salary), min(salary), avg(salary), count(*) no_of_employees
FROM departments d, employees e
WHERE e.department_id = d.department_id
GROUP BY d.department_id

结果:

ORA-00979：不是表达式的组

有人能帮我解决这个问题吗？

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请告诉我这个表达式有什么问题。

您还必须按部门名称分组

您还必须按部门名称分组

您需要按没有聚合功能的所有列（最大值、计数等）分组。因此：

select d.department_id
     , d.department_name
     , max(salary), min(salary), avg(salary) , count(*) no_of_employees
from departments d, employees e
where e.department_id = d.department_id
group by d.department_id, d.department_name;

<>但是你也应该考虑做一个ANSI连接代替：

select department_id
     , department_name
     , max(salary), min(salary), avg(salary) , count(*) no_of_employees
from departments
join employees USING (department_id)
group by department_id, department_name;

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您需要根据没有聚合函数的所有列（MAX、COUNT等）进行分组。因此：

select d.department_id
     , d.department_name
     , max(salary), min(salary), avg(salary) , count(*) no_of_employees
from departments d, employees e
where e.department_id = d.department_id
group by d.department_id, d.department_name;

<>但是你也应该考虑做一个ANSI连接代替：

select department_id
     , department_name
     , max(salary), min(salary), avg(salary) , count(*) no_of_employees
from departments
join employees USING (department_id)
group by department_id, department_name;

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谢谢你的帮助。。下面的查询适用于我选择d.department\u id、d.department\u name、max（salary）、min（salary）、avg（salary）、count（*）no\u来自d部门的员工、e员工，其中e.department\u id=d.department\u id按d.department\u id分组、部门名称感谢您的帮助。。下面的查询适用于我选择d.department\u id、d.department\u name、max（salary）、min（salary）、avg（salary）、count（*）no\u来自d部门、e员工的员工，其中e.department\u id=d.department\u id按d.department\u id、部门名称分组