HQL ERROR: Path expected for join

I keep trying variations of this query and can't seem to make this happen. I've also referenced this post: https://stackoverflow.com/questions/5759707/path-expected-for-join-nhibernate-error and can't seem to apply the same logic to my query. My User object has a UserGroup collection.

I understand that the query needs to reference entities within the object, but from what I'm seeing I am...

@NamedQuery(
  name = "User.findByGroupId",
  query =
    "SELECT u FROM UserGroup ug " +
    "INNER JOIN User u WHERE ug.group_id = :groupId ORDER BY u.lastname"
)

select u from UserGroup ug inner join ug.user u 
where ug.group_id = :groupId 
order by u.lastname

As a named query:

@NamedQuery(
  name = "User.findByGroupId",
  query =
    "SELECT u FROM UserGroup ug " +
    "INNER JOIN ug.user u WHERE ug.group_id = :groupId ORDER BY u.lastname"
)

Use paths in the HQL statement, from one entity to the other. See the Hibernate documentation on HQL and joins for details.

You need to name the entity that holds the association to User. For example,

... INNER JOIN ug.user u ...

That's the "path" the error message is complaining about -- path from UserGroup to User entity.

Hibernate relies on declarative JOINs, for which the join condition is declared in the mapping metadata. This is why it is impossible to construct the native SQL query without having the path.

You'll be better off using where clauses. Hibernate does not accept inner joins for tables where the PK/FK relationship is not there between Entities

do

SELECT s.first_name, s.surname, sd.telephone_number FROM Student s, StudentDetails sd WHERE s.id = sd.student_id

instead of

SELECT s.first_name, s.surname, sd.telephone_number FROM Student s INNER JOIN StudentDetails sd on s.id = sd.student_id

The latter will only work if Student's id (s.id) is referenced as FK on StudentDetails (sd.student_id)) table design / erd