How to set values from recursive query in PostgreSQL? - postgresql

Question

I have a query which gives a result:
id | manager_id | level | star_level
----+------------+-------+------------
1 | NULL | 1 | 0
2 | 1 | 2 | 1
3 | 2 | 3 | 1
4 | 3 | 4 | 2
5 | 4 | 5 | 2
6 | 5 | 6 | 2
7 | 6 | 7 | 3
8 | 7 | 8 | 3
9 | 8 | 9 | 4
(9 rows)
Here is the query:
WITH RECURSIVE parents AS (
SELECT e.id
, e.manager_id
, 1 AS level
, CAST(s.is_star AS INTEGER) AS star_level
FROM employees AS e
INNER JOIN skills AS s
ON e.skill_id = s.id
WHERE manager_id IS NULL
UNION ALL
SELECT e.id
, e.manager_id
, p.level + 1 AS level
, p.star_level + CAST(s.is_star AS INTEGER) AS star_level
FROM employees AS e
INNER JOIN skills AS s
ON e.skill_id = s.id
INNER JOIN parents AS p
ON e.manager_id = p.id
WHERE e.manager_id = p.id
)
SELECT *
FROM parents
;
Can you please tell me how you can change the query so that in the same query the level and star_level values ​​can be written to the corresponding columns?
Demo data:
create table Employees(
id INT,
name VARCHAR,
manager_id INT,
skill_id INT,
level INT,
star_level INT
);
create table Skills(
id INT,
name VARCHAR,
is_star BOOL
);
INSERT INTO Employees
(id, name, manager_id, skill_id)
VALUES
(1, 'Employee 1', NULL, 1),
(2, 'Employee 2', 1, 2),
(3, 'Employee 3', 2, 3),
(4, 'Employee 4', 3, 4),
(5, 'Employee 5', 4, 5),
(6, 'Employee 6', 5, 1),
(7, 'Employee 7', 6, 2),
(8, 'Employee 8', 7, 3),
(9, 'Employee 9', 8, 4)
;
INSERT INTO Skills
(id, name, is_star)
VALUES
(1, 'Skill 1', FALSE),
(2, 'Skill 2', TRUE),
(3, 'Skill 3', FALSE),
(4, 'Skill 4', TRUE),
(5, 'Skill 5', FALSE)
;
As a result, I need a query which will count level and star_level columns for Employees table and write their values (in Employees table) in one query.

Answer 1

You can use an UPDATE statement together with your CTE:
with recursive parents as (
... your original query goes here ...
)
update employees
set level = p.level,
star_level = p.star_level
from parents p
where employees.id = p.id;