private void detach_Coupon(Coupon entity)
 {
     this.SendPropertyChanging();
     entity.Product = null;
 }
 private void attach_Coupon(Coupon entity)
 {
     this.SendPropertyChanging();
     entity.Product = this;
 }
 partial void UpdateCoupon(Coupon instance);
 partial void DeleteCoupon(Coupon instance);
 partial void InsertCoupon(Coupon instance);