private void btnAdd_Click(object sender, EventArgs e) { string name = txbName.Text; DateTime birthday = dtpBirthDay.Value; string address = txbAddress.Text; string phone = txbPhone.Text; string email = txbEmail.Text; string topic = txbTopic.Text; string country = txbCountry.Text; int check; if (cbCheck.Checked == true) { check = 1; } else { check = 0; } GuestDAO _guest = new GuestDAO(); if (_guest.CheckExist(name, phone)) { MessageBox.Show("Người này đã tồn tại", "Thông Báo"); } else { _guest.AddGuest(name, birthday, address, phone, topic, email, check, country); Register next = new Register(); this.Hide(); next.Show(); } }