private void btnDangky_Click(object sender, EventArgs e) { try { command = connection.CreateCommand(); string taiKhoan = txtTaikhoan.Text; string matKhau = txtMatkhau.Text; command.CommandText = "INSERT INTO DANGNHAP (TaiKhoan, MatKhau) VALUES ('" + taiKhoan + "', '" + matKhau + "')"; command.ExecuteNonQuery(); this.Hide(); DangNhap dangNhap = new DangNhap(); dangNhap.ShowDialog(); } catch (Exception) { MessageBox.Show("Lỗi kết nối"); } }