Create a tree structure from a structured table in sql database - sql

Question

I have a table that tracks movement of data, it looks like:
From_Id
To_Id
NULL
1
1
2
NULL
3
3
4
4
5
4
6
5
7
6
10
2
8
8
9
5
9
9
NULL
10
NULL
I want to structure and store every possible paths (e.g 1,2,8,9) and im unsure about the best possible way to do this with SQL.
I started off with a simple while loop, but got a problem at id=4 where it gets 2 new paths. I tried finding a solution which uses a tree structure, but I couldnt find anything that fits my case.
What is a good solution here?
Edit:
Im using microsoft sql server
desired output:
From_Id
To_Id
path
NULL
1
1,
1
2
1,2,
NULL
3
3,
3
4
3,4,
4
5
3,4,5,
4
6
3,4,6,
5
7
3,4,5,7,
6
10
3,4,6,10,
2
8
1,2,8,
8
9
1,2,8,9,
5
9
3,4,5,9,
9
NULL
NULL
10
NULL
NULL
I tried this from How to call a recursive function in sql server
DECLARE #TABLE2 TABLE(
From_Id INT,
To_id INT
)
INSERT INTO #TABLE2 SELECT NULL,1
INSERT INTO #TABLE2 SELECT 1,2
INSERT INTO #TABLE2 SELECT NULL,3
INSERT INTO #TABLE2 SELECT 3,4
INSERT INTO #TABLE2 SELECT 4,5
INSERT INTO #TABLE2 SELECT 4,6
INSERT INTO #TABLE2 SELECT 5,7
INSERT INTO #TABLE2 SELECT 6,10
INSERT INTO #TABLE2 SELECT 2,8
INSERT INTO #TABLE2 SELECT 8,9
INSERT INTO #TABLE2 SELECT 5,9
INSERT INTO #TABLE2 SELECT 9,NULL
INSERT INTO #TABLE2 SELECT 10,NULL
;WITH Recursives AS (
SELECT *,
CAST(To_id AS VARCHAR(MAX)) + ',' ID_Path
FROM #TABLE2
WHERE From_Id IS NULL
UNION ALL
SELECT t.*,
r.ID_Path + CAST(t.To_id AS VARCHAR(MAX)) + ','
FROM #TABLE2 t INNER JOIN
Recursives r ON t.From_Id = r.To_id
)
SELECT *
FROM Recursives
Which gave me an extra row (it gets much larger when i have 10k + rows)
From_Id
To_Id
ID_Path
NULL
1
1,
1
2
1,2,
NULL
3
3,
3
4
3,4,
4
5
3,4,5,
4
6
3,4,6,
5
7
3,4,5,7,
6
10
3,4,6,10
2
8
1,2,8,
8
9
1,2,8,9,
5
9
3,4,5,9,
9
NULL
NULL
9
NULL
NULL
10
NULL
NULL

Answer 1

Create a many-to-many relationship. A new table will be created that will only store id pairs if they exist. In the case of id 4, 2 separate records will be created. Of course, if you want to display records from a new array, you can also use the select command.
The problem arises if the From_Id and To_Id fields come from the same table. In this case, an intermediate table should be created. I will use a simple one here.
An example of a social networking site. We have a user tracking feature. In this way, we create 2 instances of the follower of the user and observe. We cannot create a direct mana-to-many relationship because this cannot directly refer to the same table. We create 2 additional tables. One will save users as followers and the other as followed. It is between these tables that we create a many-to-many relationship.