Sure!
I cut off many things to make the example as simple as possible.
This is the mapping:
Code:
<class name="Task" table="Task">
      <id name="Id" column="Id" type="Int64">
         <generator class="identity"/>
      </id>
      <set name="Risorse" inverse="true" cascade="save-update">
         <key column="Task_Id"/>
         <one-to-many class="Risorsa"/>
      </set>
      <property name="StatoTask"/>
      <property name="TipoTask" type="Simplico.Business.Seteco.Entities.EnumTipoTask, SetecoEntities"/>
      <property name="DataInizio" type="Date"/>
      <property name="DataFine" type="Date"/>
      <property name="PercentualeCompletamento" type="Single"/>
   </class>
   <class name="Risorsa" table="Risorsa">
      <id name="Id" column="Id" type="Int64">
         <generator class="identity"/>
      </id>
      <many-to-one name="TaskGS" class="Task" column="Task_Id" foreign-key="fk_Risorsa_Task"/>
      <property name="DataInizio" type="Date"/>
      <property name="DataFine" type="Date"/>
      <property name="DataInserimento" type="Date"/>
      <joined-subclass name="RisorsaEconomica" table="RisorsaEconomica">
         <key column="Risorsa_Id"/>
         <property name="Valore" type="Decimal"/>
      </joined-subclass>
      <joined-subclass name="RisorsaUomo" table="RisorsaUomo">
         <key column="Risorsa_Id"/>
         <property name="Ore" type="Single"/>
         <many-to-one name="RelazioneGS" class="Simplico.Business.Anagrafica.Entities.Relazione" column="Relazione_Id" foreign-key="fk_Risorsa_Relazione"/>
      </joined-subclass>
   </class>
And this is a sample query:
Code:
string qry = "SELECT sum(ris.Ore) FROM Task t INNER JOIN t.Risorse ris GROUP BY ris.DataInizio";
The resulting query is:
Code:
select sum(risorse1_2_.Ore) as x0_0_ from Task task0_ inner join Risorsa risorse1_ on task0_.Id=risorse1_.Task_Id group by  risorse1_.DataInizio
The resulting error is quite obvious, risorse1_2_ doesn't exist.
Changing the mapping file having only one table for the hierarchy, with discriminators, everything goes fine.