If you are doing a query on bank accounts and how they relate to a bank, then you will want to have a many-to-one association in your mapping file.
As an example, here is a snippet for one that I have done, where many reservations are associated with one guest:
Code:
<hibernate-mapping>
   <class name="domain.Reservation" table="reservations">
      <id
         name="key"
         column="id"
         type="integer">
         <generator class="native"/>
      </id>      
      <property
         name="date"
         column="resDate"
         type="date"/>
      <property
         name="time"
         column="resTime"
         type="time"/>      
<!-- guest corresponds to the attribute 'guest' in my reservation class,
       while guestId is the reference made to the Guest, from this entry.
-->
      <many-to-one             
           name="guest"
           column="guestId"
           class="domain.Guest"
           fetch="join"
           lazy="false"/>
           
   </class>
</hibernate-mapping>
Hope this helps.