mysql stored procedure that calls itself recursively

Question

I have the following table:

id | parent_id | quantity
-------------------------
1  | null      | 5
2  | null      | 3
3  | 2         | 10
4  | 2         | 15         


        

Answer 1

How about avoiding procedures:

SELECT quantity from (
 SELECT @rq:=parent_id as id, @val:=@val*quantity as quantity from (
  select * from testTable order by -id limit 1000000 # 'limit' is required for MariaDB if we want to sort rows in subquery
 ) t # we have to inverse ids first in order to get this working...
 join
 ( select @rq:= 6 /* example query */, @val:= 1 /* we are going to multiply values */) tmp
 where id=@rq
) c where id is null;

Check out Fiddle!

Note! this will not work if row's parent_id>id.

Cheers!