mysql: how to save ORDER BY after LEFT JOIN without reorder?

Question

I\'ve two table:

1) profiles

+----+---------+
| id | name    |
+----+---------+
|  1 | WILLIAM |
|  2 | JOHN    |
|  3 | ROBERT  |
|  4 | MI         


        

Answer 1

I know this question is a couple of years old, but I didn't find this possible solution already offered. This is the solution that worked best for me to keep the subquery results in the correct order.

Consider adding a "row_number" to your subquery. Then use ORDER BY on row_number.

This explains how to add the row_number: select increment counter in mysql

In my case, I have an unknown number of possible rows in a hierarchical recursive query that I need to keep the order results of the subquery to remain the same in the outer query.

This is my query:

SELECT l.row_number, l.userid, l.child, p.id, p.username
FROM (

    SELECT  @rownum := @rownum + 1 AS row_number, u.parent AS userid, _id  AS child 
                FROM (
                    SELECT  @r AS _id, (SELECT  @r := parent FROM new_clean WHERE userid = _id) AS parent
                                FROM (SELECT @r := ?) AS vars, new_clean h
                                WHERE   @r <> 0 
                    ) u
                CROSS JOIN (SELECT @rownum := 0) r
                WHERE u.parent <> 0                     
    ) l 

        LEFT JOIN profile p ON p.userid = l.userid
        ORDER BY row_number