MariaDB 10.5

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create table cat(
     id int auto_increment primary key,
     url varchar(50),
     parent int references cat(id)
)
insert into cat (url, parent) values
('home', null),
('user', 1),
('apps', 1),
('nick', 2),
('excel', 3),
('word', 3),
('docs', 4)

Records: 7  Duplicates: 0  Warnings: 0


select *
from cat


id
url
parent


1
home
null

2
user
1

3
apps
1

4
nick
2

5
excel
3

6
word
3

7
docs
4


WITH RECURSIVE urls AS (
  SELECT url, parent
  FROM cat
  WHERE id = 7
  UNION ALL
  SELECT CONCAT_WS('/', cat.url, urls.url), cat.parent
  FROM urls
  JOIN cat ON cat.id = urls.parent
)
SELECT CONCAT('http://', url) AS url
FROM urls
WHERE parent IS NULL


url


http://home/user/nick/docs


WITH RECURSIVE urls AS (
  SELECT id, url, parent
  FROM cat
  UNION ALL
  SELECT urls.id, CONCAT_WS('/', cat.url, urls.url), cat.parent
  FROM urls
  JOIN cat ON cat.id = urls.parent
)
SELECT CONCAT('http://', url) AS url
FROM urls
WHERE parent IS NULL


url


http://home

http://home/apps

http://home/user

http://home/apps/excel

http://home/apps/word

http://home/user/nick

http://home/user/nick/docs