public void ProviderToDemandDelete(T_ProviderToDemand providerToDemand)
 {
     _providerToDemandTable.Remove(providerToDemand);
 }
 public void DemandToProviderDelete(T_DemandToProvider demandToProvider)
 {
     _demandToProviderTable.Remove(demandToProvider);
 }