partial void Deletetlb_diemhk(tlb_diemhk instance);
 partial void Inserttlb_diemhk(tlb_diemhk instance);
 partial void Updatetlb_diemhk(tlb_diemhk instance);
 private void detach_tlb_diemhks(tlb_diemhk entity)
 {
     this.SendPropertyChanging();
     entity.tlb_sinhvien = null;
 }