How To Get First Parent By Child ID With MySql Query Or php?

Question

I have this table:

id	name	parent_id
1	mike	0
2	jeff	0
3	bill	2
4	sara	1
5	sam	4
6	shai	5

I want to find first parent name,id by send id OR parent_id:

For example:

If I Send 6 id(shai) I want To Show That The First Parent That Name Is mike(id:1) But My Query Only Shows Previous parent and When I send 6 As id It Only Show sam(id:5). How Can I Find First Parent By SQL Query Or Php Code?

This Is My Code:

SELECT child.id, child.name, child.parent_id, parent.name as ParentName FROM test child JOIN test parent ON child.parent_id = parent.id WHERE child.id=6;

Answer 1

 CREATE TABLE test (id INT, name VARCHAR(255), parent_id INT); INSERT INTO test VALUES (1, 'mike', 0), (2, 'jeff', 0), (3, 'bill', 2), (4, 'sara', 1), (5, 'sam', 4), (6, 'shai', 5); SELECT * FROM test;

id	name	parent_id
1	mike	0
2	jeff	0
3	bill	2
4	sara	1
5	sam	4
6	shai	5

 CREATE FUNCTION get_most_parent (id INT) RETURNS CHAR(255) BEGIN DECLARE parent_name VARCHAR(255); REPEAT SELECT name, parent_id INTO parent_name, id FROM test WHERE test.id = id; UNTIL NOT id END REPEAT; RETURN parent_name; END

 SELECT test.*, get_most_parent(id) TopParentName FROM test WHERE id IN (3, 6);

id	name	parent_id	TopParentName
3	bill	2	jeff
6	shai	5	mike

db<>fiddle here

PS. Apply this method only to single user or tiny users set - the function executes the whole iterative selection process for each output row separately and independently. And avoid cycles in your data!