partial void Deletesach(sach instance);
 partial void Updatesach(sach instance);
 private void detach_saches(sach entity)
 {
     this.SendPropertyChanging();
     entity.loai = null;
 }
 partial void Insertsach(sach instance);
 private void attach_saches(sach entity)
 {
     this.SendPropertyChanging();
     entity.loai = this;
 }