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[b]Hibernate version:[/b] hibernate-3.0

[b]Mapping documents:[/b]
<hibernate-mapping>
<class name="Resource" table="resource">
<id column="ResourceId" name="id" type="java.lang.Long">
<generator class="native"/>
</id>

<property column="ResourceName" length="255" name="resourcename" not-null="true" type="java.lang.String"/>

<joined-subclass name="Managedresource" table="managedresource" >
<key column="ResourceId"/>
<property column="ManagementMethodSupported" length="255" name="managementmethodsupported" not-null="true"
type="java.lang.String"/>
</joined-subclass>
</class>
</hibernate-mapping>

class Managedresource extends Resource.

I use "Table per subclass" create DB and mapping files.
when I query Resource, the sql use "outer" to find out all result include Managedresource. How can I stop to use "outer" sql? I wanna get Resource result only when I query Resource

This has got to be my most-frequently-asked question, recently :)

Hibernate is aware that all rows in Resource might be ManagedResources. Any instances of ManagedResource MUST be loaded with all columns from both tables. Polymorphism requires this: a ManagedResource with only its Resource values is not a ManagedResource. Therefore, all Resources will always be loaded with that outer join, in case any of them are ManagedResources.

If you use delegation instead of inheritance, then you can choose if you want the inner or outer join in the normal way. This would mean that ManagedResource doesn't extend Resource: instead, some Resource objects will have a ManagedResource object inside of them, and they'd delegate ManagedResource properties to that object.