Using JOIN with cte - oracle

Question

I have the following setup, which seems to be working fine. I am having trouble modifying the query to include the department_name in the output.
I can't seem to get the JOIN working with the CTE. Its probably something trivial but after many attempts I can't get it to work.
Any help would be appreciated.
Below is my setup and test case.
CREATE TABLE departments( department_id, department_name) AS
SELECT 1, 'IT' FROM DUAL UNION ALL
SELECT 2, 'DBA' FROM DUAL;
CREATE TABLE employees (employee_id, first_name, last_name, hire_date, salary, department_id) AS
SELECT 1, 'Lisa', 'Saladino', DATE '2001-04-03', 100000, 1 FROM DUAL UNION ALL
SELECT 2, 'Abby', 'Abbott', DATE '2001-04-04', 50000, 1 FROM DUAL UNION ALL
SELECT 3, 'Beth', 'Cooper', DATE '2001-04-05', 60000, 1 FROM DUAL UNION ALL
SELECT 4, 'Carol', 'Orr', DATE '2001-04-06', 70000,1 FROM DUAL UNION ALL
SELECT 5, 'Vicky', 'Palazzo', DATE '2001-04-07', 88000,2 FROM DUAL UNION ALL
SELECT 6, 'Cheryl', 'Ford', DATE '2001-04-08', 110000,1 FROM DUAL UNION ALL
SELECT 7, 'Leslee', 'Altman', DATE '2001-04-10', 666666, 1 FROM DUAL UNION ALL
SELECT 8, 'Jill', 'Coralnick', DATE '2001-04-11', 190000, 2 FROM DUAL UNION ALL
SELECT 9, 'Faith', 'Aaron', DATE '2001-04-17', 122000,2 FROM DUAL;
WITH cte AS (
SELECT department_id,
first_name,
last_name,
salary,
DENSE_RANK() OVER(PARTITION BY department_id ORDER BY salary DESC) AS rnk
FROM employees
)
SELECT department_id,
/* department_name */
first_name,
last_name,
salary
FROM cte
WHERE rnk=1

Answer 1

You did not join the table.
WITH cte AS (
SELECT department_id,
first_name,
last_name,
salary,
DENSE_RANK() OVER(PARTITION BY department_id ORDER BY salary DESC) AS rnk
FROM employees
)
SELECT e.department_id,
d.department_name,
e.first_name,
e.last_name,
e.salary
FROM cte e
INNER JOIN departments d
ON (d.department_id = e.department_id)
WHERE rnk=1
or:
WITH cte AS (
SELECT e.department_id,
d.department_name,
e.first_name,
e.last_name,
e.salary,
DENSE_RANK() OVER(PARTITION BY e.department_id ORDER BY e.salary DESC) AS rnk
FROM employees e
INNER JOIN departments d
ON (d.department_id = e.department_id)
)
SELECT department_id,
department_name,
first_name,
last_name,
salary
FROM cte
WHERE rnk=1
or using a sub-query, instead of the sub-query factoring clause:
SELECT e.department_id,
d.department_name,
e.first_name,
e.last_name,
e.salary
FROM (
SELECT department_id,
first_name,
last_name,
salary,
DENSE_RANK() OVER(PARTITION BY department_id ORDER BY salary DESC) AS rnk
FROM employees
) e
INNER JOIN departments d
ON (d.department_id = e.department_id)
WHERE rnk=1
or:
SELECT department_id,
department_name,
first_name,
last_name,
salary
FROM (
SELECT e.department_id,
d.department_name,
e.first_name,
e.last_name,
e.salary,
DENSE_RANK() OVER(PARTITION BY e.department_id ORDER BY e.salary DESC) AS rnk
FROM employees e
INNER JOIN departments d
ON (d.department_id = e.department_id)
)
WHERE rnk=1
fiddle