private void cboChonTenDangNhap_SelectedValueChanged(object sender, EventArgs e)
        {
            ComboBox     cb    = sender as ComboBox;
            BEL_TAIKHOAN value = cb.SelectedValue as BEL_TAIKHOAN;

            name = value.TenDangNhap;
        }
        public List <BEL_TAIKHOAN> load_User()
        {
            List <BEL_TAIKHOAN> list_user = new List <BEL_TAIKHOAN>();
            string     query = "SELECT UserName FROM dbo.Account";
            SqlCommand cmd   = new SqlCommand(query, Getcon());

            //DataTable ds = new DataTable();
            try
            {
                SqlDataReader rd = cmd.ExecuteReader();
                dt.Load(rd);
                foreach (DataRow item in dt.Rows)
                {
                    BEL_TAIKHOAN user = new BEL_TAIKHOAN(item);
                    list_user.Add(user);
                }
            }
            catch (Exception err)
            {
                throw;
            }
            return(list_user);
        }