Q: Get ancestors with a node in mysql - php

Question

Here is the reference link that I used to create procedures: https://dba.stackexchange.com/questions/7147/find-highest-level-of-a-hierarchical-field-with-vs-without-ctes/7161#7161?newreg=88de047579d242c98b8cfe0e17f0330f
Procedures are working well with the example. But not working in my own database. Seems I do something wrong while creating procedures.
Here is the procedure for my db:
DELIMITER $$
DROP FUNCTION IF EXISTS `demo`.`GetParentIDByID` $$
CREATE FUNCTION `demo`.`GetParentIDByID` (GivenID INT) RETURNS INT
DETERMINISTIC
BEGIN
DECLARE rv INT;
SELECT IFNULL(user_by,-1) INTO rv FROM
(SELECT user_by FROM users WHERE id = GivenID) A;
RETURN rv;
END $$
DELIMITER ;
Sql query for the following procedure is working fine. It is basically getting parent_id of the node:
SELECT id,GetParentIDByID(id) FROM users;
Issue occurs when I am try to get Ancestors. Here is the Procedure that I am using:
DELIMITER $$
DROP FUNCTION IF EXISTS `demo`.`GetAncestry` $$
CREATE FUNCTION `demo`.`GetAncestry` (GivenID INT) RETURNS VARCHAR(1024)
DETERMINISTIC
BEGIN
DECLARE rv VARCHAR(1024);
DECLARE cm CHAR(1);
DECLARE ch INT;
SET rv = '';
SET cm = '';
SET ch = GivenID;
WHILE ch > 0 DO
SELECT IFNULL(user_by,-1) INTO ch FROM
(SELECT user_by FROM users WHERE id = ch) A;
IF ch > 0 THEN
SET rv = CONCAT(rv,cm,ch);
SET cm = ',';
END IF;
END WHILE;
RETURN rv;
END $$
DELIMITER ;
SQL query:
SELECT id,GetAncestry(id) FROM users;
Phpmyadmin getting stuck, if I am using this query. It never returns me anything nor an error or success