Recursive CTE - Get descendants (many-to-many relationship)

Question

What I have:

Given a tree (or more like a directed graph) that describes how a system is composed by its generic parts. For now let this system be e.g. the human body

Answer 1

Problem solved, here is the query I needed, I hope it once helps someone else too...

WITH RECURSIVE graph AS (
  SELECT
    p.id AS subpart,
    pp.cont AS part
  FROM part p JOIN partpart pp
  ON p.id = pp.part
  WHERE pp.cont = 3
  UNION ALL
  SELECT
    part.id,
    partpart.cont
  FROM (part JOIN partpart
  ON part.id = partpart.part
  ), graph WHERE partpart.cont = graph.subpart
)
SELECT part, subpart, FROM graph