partial void Deleteborrower(borrower instance);
 partial void Updateborrower(borrower instance);
 private void detach_borrowers(borrower entity)
 {
     this.SendPropertyChanging();
     entity.book = null;
 }
 partial void Insertborrower(borrower instance);
 private void attach_borrowers(borrower entity)
 {
     this.SendPropertyChanging();
     entity.book = this;
 }