postgres tutorial 8 with, recursive

Common Table Expressions only exist during the execution of the query.

WITH cte_film AS (
    SELECT
        film_id,
        title,
        (CASE
            WHEN length < 30 THEN 'Short'
            WHEN length >= 30 AND length < 90 THEN 'Medium'
            WHEN length > 90 THEN 'Long'
        END) length   
    FROM
        film
)
SELECT
    film_id,
    title,
    length
FROM
    cte_film
WHERE
    length = 'Long'
ORDER BY
    title;

-----------------------------------
INSERT INTO employees (
 employee_id,
 full_name,
 manager_id
)
VALUES
 (1, 'Michael North', NULL),
 (2, 'Megan Berry', 1),
 (3, 'Sarah Berry', 1),
 (4, 'Zoe Black', 1),
 (5, 'Tim James', 1),
 (6, 'Bella Tucker', 2),
 (7, 'Ryan Metcalfe', 2),
 (8, 'Max Mills', 2),
 (9, 'Benjamin Glover', 2),
 (10, 'Carolyn Henderson', 3),
 (11, 'Nicola Kelly', 3),
 (12, 'Alexandra Climo', 3),
 (13, 'Dominic King', 3),
 (14, 'Leonard Gray', 4),
 (15, 'Eric Rampling', 4),
 (16, 'Piers Paige', 7),
 (17, 'Ryan Henderson', 7),
 (18, 'Frank Tucker', 8),
 (19, 'Nathan Ferguson', 8),
 (20, 'Kevin Rampling', 8);

 WITH RECURSIVE subordinates AS (
 SELECT
 employee_id,
 manager_id,
 full_name
 FROM
 employees
 WHERE
 employee_id = 2
 UNION
 SELECT
 e.employee_id,
 e.manager_id,
 e.full_name
 FROM
 employees e
 INNER JOIN subordinates s ON s.employee_id = e.manager_id
) SELECT
 *
FROM
 subordinates;

first round

 employee_id | manager_id |  full_name
-------------+------------+-------------
           2 |          1 | Megan Berry
 
second round

 employee_id | manager_id |    full_name
-------------+------------+-----------------
           6 |          2 | Bella Tucker
           7 |          2 | Ryan Metcalfe
           8 |          2 | Max Mills
           9 |          2 | Benjamin Glover
 
third round

employee_id | manager_id |    full_name
-------------+------------+-----------------
          16 |          7 | Piers Paige
          17 |          7 | Ryan Henderson
          18 |          8 | Frank Tucker
          19 |          8 | Nathan Ferguson
          20 |          8 | Kevin Rampling
 
union all

employee_id | manager_id |    full_name
-------------+------------+-----------------
           2 |          1 | Megan Berry
           6 |          2 | Bella Tucker
           7 |          2 | Ryan Metcalfe
           8 |          2 | Max Mills
           9 |          2 | Benjamin Glover
          16 |          7 | Piers Paige
          17 |          7 | Ryan Henderson
          18 |          8 | Frank Tucker
          19 |          8 | Nathan Ferguson
          20 |          8 | Kevin Rampling
(10 rows)