I have a one-to-one relationship between Vehicle and Device with unique foreign key.
table vehicles
vehicle_id
...
table devices
device_id pk
vehicle_id


For the Device object I have this:
<many-to-one name="Vehicle" column="vehicle_id" class="Vehicle" unique="true" cascade="none"/>

and for the Vehicle object I have this:
<one-to-one name="Device" class="Device" property-ref="Vehicle" />

I'm trying to find all Vehicle objects that do not have associated Device object using this:
vehicles = session.CreateCriteria(typeof(Vehicle))
.Add(Expression.IsNull("Device"))
.List();

This returns empty set because the generated SQL is wrong. This is it:
SELECT ..... FROM
vehicles this
left outer join devices device1_ on this.vehicle_id=device1_.vehicle_id
WHERE this.vehicle_id is null

The Where clause here should be:
WHERE device1_.vehicle_id is null

Am I doing something wrong?


Hibernate version:
1.02

Can anyone help or explain what is the problem?

I believe I had the same problem as described above. I found a suitable workaround offered in the "Advanced Problems" FAQ under the heading "The query language IS NULL syntax won't work with a one-to-one association!"

The solution worked for me! Hope this helps. I swore I would post an answer if I found one. Hope this helps.

It's probably a bug, but try version 1.2.0, 1.0.2 is quite old.