How do I left join tables in unidirectional many-to-one in Hibernate?
- by jbarz
I'm piggy-backing off of http://stackoverflow.com/questions/2368195/how-to-join-tables-in-unidirectional-many-to-one-condition.
If you have two classes:
class A {
@Id
public Long id;
}
class B {
@Id
public Long id;
@ManyToOne
@JoinColumn(name = "parent_id", referencedColumnName = "id")
public A parent;
}
B - A is a many to one relationship. I understand that I could add a Collection of Bs to A however I do not want that association.
So my actual question is, Is there an HQL or Criteria way of creating the SQL query:
select * from A left join B on (b.parent_id = a.id)
This will retrieve all A records with a Cartesian product of each B record that references A and will include A records that have no B referencing them.
If you use:
from A a, B b where b.a = a
then it is an inner join and you do not receive the A records that do not have a B referencing them.
I have not found a good way of doing this without two queries so anything less than that would be great.
Thanks.
