我需要一些oracle sql的帮助。问题:我有2个员工和部门表。我从一个查询得到了平均部门薪水,我想用它来看看有多少员工赚的钱多于他们部门的平均水平。到目前为止,我有这个。
此查询返回部门的平均值:
select ROUND(AVG(Salary), 2) Dept_avg_sal
from employee, department
where department.department_id = employee.department_id
group by department_name
我想做的是:
select employee_name,
salary,
d.department_name
from employee e,
department d
where salary > (select ROUND(AVG(Salary), 2) Dept_avg_sal
from employee,
department
where department.department_id = employee.department_id
group by department_name)
我得到的错误是:01427。 00000 - “单行子查询返回多行”
我知道同一部门的2名员工赚的钱多于平均水平,我认为这是造成这个问题的原因。
EMPLOYEE_NAME - SALARY - -DEPARTMENT_NAME- DEPT_AVG_SAL
-------------------- ---------------------- -------------------- ------------
FISHER - 3000.00 - SALES - 2500.00
JONES - 3000.00 - ACCOUNTING - 2750.00
KING - 5000.00 - EXECUTIVE - 4500.00
**SCOTT - 2500.00 - IT - 2100.00
SMITH - 2900.00 - IT - 2100.00**
WILSON - 3000.00 - RESEARCH - 2633.33
任何帮助都会非常感激。
答案 0 :(得分:7)
您的初始查询缺少外部查询的任何连接条件以及内部查询中的任何相关条件,这些条件将仅限于感兴趣的部门的行。通常,您也不希望group by name
,因为大概是id
SELECT e.employee_name,
e.salary,
d.department_name
FROM employee e
JOIN department d
ON d.department_id = e.department_id
WHERE e.salary > (SELECT ROUND(AVG(Salary), 2) Dept_avg_sal
FROM employee e2
WHERE e2.department_id = e.department_id)
。
解决这些问题以修复相关子查询得出
SELECT e.employee_name,
e.salary,
d.department_name
FROM employee e
JOIN department d
ON d.department_id = e.department_id
JOIN (SELECT ROUND(AVG(Salary), 2) Dept_avg_sal,
department_id
FROM employee
GROUP BY department_id) e2
ON e2.department_id = e.department_id
AND e.salary > e2.Dept_avg_sal
但是你可能会发现放弃标量相关的子查询并用派生表替换效果会更好。
SELECT employee_name,
salary,
d.department_name
FROM (SELECT employee_name,
salary,
d.department_name,
AVG(Salary) OVER (PARTITION BY e.department_id) AS AvgSalary
FROM employee e
JOIN department d
ON d.department_id = e.department_id)
WHERE salary > AvgSalary
对于Oracle,我认为以下也应该有效
{{1}}
答案 1 :(得分:1)
> operator只接受一个值,因此你的内部SELECT必须返回1行。我的猜测是你获得了多行。查看内部SELECT返回的内容并尝试LIMIT 1。
答案 2 :(得分:1)
我认为你应该在子查询中添加额外的d.department_id = department.department_id
条件(未经测试):
select employee_name,
salary,
d.department_name
from employee e,
department d
where salary > (select ROUND(AVG(Salary), 2) Dept_avg_sal
from employee,
department
where department.department_id = employee.department_id
AND d.department_id = department.department_id
group by department_name)
或者只写:
select e.employee_name,
e.salary,
d.department_name
from employee e,
department d
where e.department_id = d.department_id
AND salary > (select ROUND(AVG(Salary), 2) Dept_avg_sal
from employee
where e.department_id = employee.department_id)