Updating a parent and its children without link between them - postgresql

Question

I'm facing an issue and hope you will be able to guide me in the right direction.
A facility can have 1..n sub-facilities. Sub-facilities can have 1..n sub-facilities as well. And this can be a never ending relationship.
In the database, we only have keys to connect the parent and first children.
Here's a short schema:
--Facility has : facilityid|parentid
---child1 has : facilityid|parentid to facility
----child2 has : facilityid|parentid to child 1 / no key to main parent
-----child2 has : facilityid|parentid to child 2 / no key to main parent
What I am trying to do is update a column named value and set it to true for a parent and all of its children and sub-children included. Right now, since I am only able to see the first parent and its children but not the sub-children, I can only update the value of those. But that leaves all my sub-children not updated.
Knowing that there is no link between sub-children and main parent, how would I accomplish that?
Here's a query that gives me a parent and all of its children.
WITH attributes AS (
select fa.facilityid, a.id
from caip_attribute a
join caip_facility_attribute fa on a.id = fa.attributeid)
select a.facilityid as parentfacilityid, a.id as parentattributeid, f.id as facilitychildid, fa.attributeid as childattributeid
from attributes a
join caip_facility f on f.parentid = a.facilityid
join caip_facility_attribute fa on fa.facilityid = f.id
join caip_attribute at on at.id = fa.attributeid
where at.definitionTypeKey = 'AUTO_CREATE_PROCESS'
order by f.id asc
The update statement is missing here but this is how I get the values that will later need to be updated.
Thank you!

Answer 1

To update all descendants of a parent you can use a recursive CTE.
Suppose we have a data table with relations set using self-referencing foreign key column parent_id:
CREATE TABLE t (
id SERIAL PRIMARY KEY,
value BOOL DEFAULT FALSE,
parent_id INT,
FOREIGN KEY (parent_id) REFERENCES t(id)
);
First, a query that returns a parent with id = 1 and all it's descendants would be like this:
WITH RECURSIVE children(id, value, parent_id) AS (
SELECT id, value, parent_id FROM t WHERE id = 1
UNION
SELECT t.id, t.value, t.parent_id FROM t
INNER JOIN children ON children.id = t.parent_id
)
SELECT * FROM children
Second, to update a value of parent and all it's descendants we can set value for all rows with ids in our select query:
UPDATE t SET value = true
WHERE id IN (
WITH RECURSIVE children(id, value, parent_id) AS (
SELECT id, value, parent_id FROM t WHERE id = 1
UNION
SELECT t.id, t.value, t.parent_id FROM t
INNER JOIN children ON children.id = t.parent_id
)
SELECT id FROM children
)
Check a demo