private void TaoMaXacNhan()
{
string code = "";
string email, username;
email = txtEmail.Text;
username = txtUsername.Text;
code = Ham.RamdomCode(6);
cn.ExecuteNonQuery("UPDATE HTUser set Code = '" + code + "' where email = '" + email + "' and taikhoan = '" + username + "'");
GuiMa(code);
}