How to write recursion in mysql?

Question

MySQL

Hello!
Such a task. We need to find the total population.
It must be done through recursion.
I'm trying to do this:

CREATE PROCEDURE `GetChildrenObjects3`
  (IN `Parent` BIGINT, OUT `total` BIGINT)
BEGIN
  DECLARE population int;
  DECLARE total2 int DEFAULT 0 ;
  DECLARE irows int ;

  SET irows = (SELECT COUNT(d.Population) FROM MDepartments d
    LEFT JOIN Localities l ON d.LocalityId = l.Id WHERE d.ParentId = Parent AND Type = 0);

  IF irows>=1 THEN

    SET total = (SELECT SUM(d.Population) FROM MDepartments d
      LEFT JOIN Localities l ON d.LocalityId = l.Id WHERE d.ParentId = Parent AND Type = 0);

    SELECT d.MOId, SUM(d.Population)  FROM MDepartments d
      LEFT JOIN Localities l ON d.LocalityId = l.Id WHERE d.ParentId = Parent AND Type = 0;

    CALL GetChildrenObjects3(d.MOId);
  ELSE
    SET total = NULL;
  END IF;
END

There are tables, and they can have child objects. It is necessary to go there and summarize the population by parent populations.
Help how?

Answer 1

This decision is in the style - "let's go to the rally on an asphalt skating rink, we know how to manage it, and it doesn't go very fast, we won't fly off the track!".
Select all the values ​​​​by queries into something more programmatic, and twist there, it will be faster, more reliable and more logical.
For example, python, php, java, and almost any language you know will be better than this.