Oracle show all employees with greater than average salary of their department

Question

I am writing a query to find employees who earn greater than the average salary within their department. I need to display the employee ID, salary, department id, and averag

Answer 1

I don't believe you can refer to a column alias (avg_sal in this case) in a WHERE clause.

You'll need to repeat that inner query, i.e.:

SELECT employee_id, salary, department_id,
  (SELECT ROUND(AVG(salary),2)
  FROM employees e_inner
  WHERE e_inner.department_id = e.department_id) AS avg_sal
FROM employees e
WHERE salary > 
 (SELECT ROUND(AVG(salary),2)
  FROM employees e_inner
  WHERE e_inner.department_id = e.department_id)
ORDER BY avg_sal DESC

Not great, with those two inner queries, but that's the most-straightforward way to correct the error.

Update: Haven't tested this, but try the following:

SELECT e.employee_id, e.salary, e.department_id, b.avg_sal
FROM employees e
INNER JOIN
(SELECT department_id, ROUND(AVG(salary),2) AS avg_sal
 FROM employees
 GROUP BY department_id) e_avg ON e.department_id = e_avg.department_id AND e.salary > e_avg.avg_sal
ORDER BY e_avg.avg_sal DESC