Dear all,

please give me help information for may problem.

I have in my project this model structure

D class has atributes d1, d2
A class has attributes a1, a2
D is in 0..1-0..1 association with A

A is in 0..1-0..* association with CR

N (with attributes n1 and n2) and M(with attributes m1 and m2) extend CR

How to create query that return d1, d2,n1,m1 for all D objects from those tables in case that some objects from D don't have via A associated objects N or M ?

I've tried with outer join but I havn't had result. I got emty result for existed objects D which don't have object M or N.

select d1,d2,n1,m1
from D d, M m, N n
where
d.a_id = m.a_id and
d.a_id = n.a_id

If you have some idea for my problem please help me

Thank you in advance!!!