public T_ProviderToDemand ProviderToDemandGetById(Id id)
 {
     return((T_ProviderToDemand)_providerToDemandTable.GetById(id));
 }
 public T_DemandToProvider DemandToProviderGetById(Id id)
 {
     return((T_DemandToProvider)_demandToProviderTable.GetById(id));
 }