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

Take a look at Managing Hierarchical Data in MySQL by Mike Hillyer.

It contains fully worked examples on dealing with hierarchical data.