I have the following recursive relation (E-R diagram):

soggetto-------accordo
| |
| |
|---------------|

For more flexibility I use 1-* and *-1 associations (soggetto is the same table):

soggetto--------accordo-------soggetto
1----------------*-------*----------- 1

Here my mappings:

-----SOGGETTO MAPPING--------
<hibernate-mapping>
<class
name="com.db.siscombe.database.databeans.Soggetto"
table="SOGGETTO"
schema="SISCOMBE"
>
<id
name="idSoggetto"
type="long"
column="ID_SOGGETTO"
length="22"
>
<generator class="sequence">
<param name="sequence">soggetto_seq</param>
</generator>
</id>
<property
name="codCanale"
type="string"
column="COD_CANALE"
length="9"
/>
.......

<!-- bi-directional many-to-one association to Accordo -->
<set
name="soggAccNazionales1"
lazy="true" cascade="persist"
>
<key>
<column name="ID_ACCORDO_NAZIONALE" /> <!-- a foreign key in ACCORDO referencing the primary key of this table. -->
</key>
<one-to-many class="com.db.siscombe.database.databeans.Accordo" />
</set>
<!-- bi-directional many-to-one association to Accordo -->
<set
name="soggAccNazionales2"
lazy="true" cascade="persist"
>
<key>
<column name="ID_SOGGETTO" /> <!-- a foreign key in ACCORDO referencing the primary key of this table. -->
</key>
<one-to-many class="com.db.siscombe.database.databeans.Accordo" />
</set>

-----ACCORDO MAPPING--------
<hibernate-mapping>
<class
name="com.db.siscombe.database.databeans.Accordo"
table="ACCORDO "
schema="SISCOMBE"
>
<id
name="idSoggAccNazionale"
type="long"
column="ID_SOGG_ACC_NAZIONALE"
length="22"
>
<generator class="sequence">
<param name="sequence">sogg_acc_nazionale_seq</param>
</generator>
</id>
<property
name="codIstituto"
type="string"
column="COD_ISTITUTO"
length="33"
/>
.....

<many-to-one
name="soggetto1"
class="com.db.siscombe.database.databeans.Soggetto" cascade="persist"
>
<column name="ID_ACCORDO_NAZIONALE" length="22"/>
</many-to-one>
<!-- bi-directional many-to-one association to Soggetto -->
<many-to-one
name="soggetto2"
class="com.db.siscombe.database.databeans.Soggetto" cascade="persist"
>
<column name="ID_SOGGETTO" length="22"/>
</many-to-one>

If I want to use QBE (Query by example) what is the java code to make a join soggetto---->accordo---->soggetto?