private void LoadData()
{
int id = 0;
if (Common.LoaiNguoiDungID() == 3)
{
id = 0;
}
else if (Common.LoaiNguoiDungID() == 2)
{
id = Common.NguoiDungID();
}
DonHang dh = new DonHang();
DataSet ds = dh.SelectByNguoiDungID(id);
grdDonHang.DataSource = ds.Tables[0];
grdDonHang.DataBind();
}