How to retrieve all recursive children of parent row in Oracle SQL?

Question

I\'ve got a recursive query that\'s really stretching the limits of this Java monkey\'s SQL knowledge. Now that it\'s finally 1:30 in the AM, it\'s probably time to start looki

Answer 1

@AlexPoole answer is great, I just want to extend his answer with more intuitive variant of query for summing values along a path.
This variant based on recursive subquery factoring feature, introduced in Oracle 11g R2.

with recursion_view(base, parent_id, child_id, qty) as (
   -- first step, get rows to start with
   select 
     parent_id base, 
     parent_id, 
     child_id, 
     qty
  from 
    md_boms

  union all

  -- subsequent steps
  select
    -- retain base value from previous level
    previous_level.base,
    -- get information from current level
    current_level.parent_id,
    current_level.child_id,
    -- accumulate sum 
    (previous_level.qty + current_level.qty) as qty 
  from
    recursion_view previous_level,
    md_boms        current_level
  where
    current_level.parent_id = previous_level.child_id

)
select 
  base, parent_id, child_id, qty
from 
  recursion_view
order by 
  base, parent_id, child_id

SQLFiddle example (extended with one data row to demonstrate work with more then 2 levels)