Recursively get nested URLs from database - sql

Question

I have a Database table structured with nested URLs, using ParentID and ID to tell which piece of an URL belongs where.
Table structure looks like this:
+-----+----------+------------+-------------+
| ID | ParentID | Name | Url |
+-----+----------+------------+-------------+
| 1 | 0 | Categories | categories |
| 34 | 1 | Movies | movies |
| 281 | 34 | Star Wars | star-wars |
| 33 | 1 | Books | a-good-book |
+-----+----------+------------+-------------+
What I want to do is that I want to be able to recursively go through all of the fields, and according to the ParentID, save all the possible url combinations.
So, from the table above, I'd like to get the following output:
mysite.com/categories
mysite.com/categories/movies
mysite.com/categories/movies/star-wars
mysite.com/categories/books
mysite.com/categories/books/a-good-book
I've started writing a CTE, looking like this:
WITH CategoriesCTE AS
(
SELECT
Name,
Url,
ParentID,
ID
FROM myDB
WHERE ParentID = 1
UNION ALL
SELECT
a.Name,
a.Url,
a.ParentID,
a.ID
FROM myDB.a
INNER JOIN CategoriesCTE s on a.ParentID = s.ID
)
SELECT * FROM CategoriesCTE
Thing is, this database call saves everything flat. What I would have to do, is that for EACH step, save all urls, and then for each ID, save the url according to what the ParentID is. Right now it of course isn't formatted but my output is flatly something like:
mysite.com/categories
mysite.com/movies
mysite.com/star-wars
mysite.com/a-good-book
Which creates a lot of broken links.
Is there some way to do an action/select for each recursive step? How should I be approaching this problem?

Answer 1

Add a few of new fields to your recursive CTE to track:
Depth of recursion (so you can find the record with the greatest depth
The path which will be built through each iteration by concatenating the latest value to it.
The starting point of the recursion so you know what record you started with
WITH CategoriesCTE AS
(
SELECT Name, Url, ParentID, ID, 1 as depth, CAST(url as VARCHAR(500)) as path, url as startingpoint
FROM myDB
WHERE ParentID = 1
UNION ALL
SELECT a.Name, a.Url, a.ParentID, a.ID, s.depth + 1, a.url + s.path, s.url
FROM myDB.a
INNER JOIN CategoriesCTE s on a.ParentID = s.ID
)
SELECT * FROM CategoriesCTE

Answer 2

See what you think of this...
IF OBJECT_ID('tempdb..#SomeTable', 'U') IS NOT NULL
DROP TABLE #SomeTable;
CREATE TABLE #SomeTable (
ID INT NOT NULL,
ParentID INT NOT NULL,
FolderName VARCHAR(20) NOT NULL,
UrlPath VARCHAR(8000) NULL
);
INSERT #SomeTable (ID, ParentID, FolderName) VALUES
(1 , 0 , 'categories'),
(34 , 1 , 'movies'),
(281, 34, 'star-wars'),
(33 , 1 , 'a-good-book');
-- SELECT * FROM #SomeTable st;
WITH
cte_Categories AS (
SELECT
SitePath = CAST(CONCAT('mysite.com/', st.FolderName) AS VARCHAR(8000)),
st.ID,
NodeLevel = 1
FROM
#SomeTable st
WHERE
st.ParentID = 0
UNION ALL
SELECT
SitePath = CAST(CONCAT(c.SitePath, '/', st.FolderName) AS VARCHAR(8000)),
st.ID,
nodeLevel = c.NodeLevel + 1
FROM
cte_Categories c
JOIN #SomeTable st
ON c.ID = st.ParentID
)
SELECT
c.SitePath,
c.ID,
c.NodeLevel
FROM
cte_Categories c;