get ALL last level children (leafs) from a node (hierarhical queries Oracle 11G)

Question

I am trying and searching the way to get ALL last level children (leafs) from a node, in a hierchical query in Oracle 11g database.

I have 2 tables

Answer 1

You can simply use CONNECT_BY_ISLEAF.

SELECT n.id, n.val
FROM NODES n 
LEFT JOIN RELATION r ON (n.id = r.id_child)
WHERE CONNECT_BY_ISLEAF = 1
CONNECT BY PRIOR n.id = r.id_father
START WITH r.id_father IS NULL