private void btnRemove_Click(object sender, EventArgs e)
        {
            StudenAccess stdac = new StudenAccess();

            try
            {
                student std = new student
                {
                    C01_id          = int.Parse(txtID.Text),
                    C02_firtsname   = txtFirstName.Text,
                    C03_lastname    = txtLastName.Text,
                    C04_birthday    = timeBirthday.Value,
                    C05_gender      = radMale.Checked,
                    C06_phonenumber = txtPhone.Text,
                    C07_address     = txtAddress.Text,
                    //C08_avatar = new Binary(AllUser.ImageToBinary(picAvatar.Image))
                };
                stdac.Remove(std);
                this.Close();
            }
            catch (System.Data.SqlClient.SqlException ex)
            {
                MessageBox.Show(ex.Message, null, MessageBoxButtons.OK, MessageBoxIcon.Warning);
            }
        }