try
        {
            con.Open();
            SqlDataReader myReader = null;
            SqlCommand myCom = new SqlCommand("select ID,client from tposClient where CardNo='" + cNo + "'", con);

            myReader = myCom.ExecuteReader();

            Panel panel1 = new Panel();
            panel1.Style["text-align"] = "Center";
            panel1.Style["background"] = "blue";
            div_login.Visible = false;

            while (myReader.Read())
            {
                string b = myReader["client"].ToString();
                string id = myReader["ID"].ToString();

                Button btn = new Button();
                btn.Text = b;
                btn.ID = id;
                btn.Style["width"] = "100px";
                btn.Click += new EventHandler(btn_Click);
                panel1.Controls.Add(btn);

                panel1.Controls.Add(new LiteralControl("<br />"));
                form1.Style.Add("display", "block");
                form1.Controls.Add(panel1);
            }
        }
        catch (Exception k)
        {
            Console.WriteLine(k.ToString());
        }
        finally
        {
            cmdselect.Dispose();
            if (con != null)
            {
                con.Close();
            }
        }

<asp:ListView ID="lv1" runat="server" OnItemDataBound="lv1_ItemDataBound">
    <ItemTemplate>
        <asp:Button ID="btn1" runat="server" Text="my Text />
    </ItemTemplate>
</asp:ListView>

//Your data access code
Dictionary<string, string> buttonIdsWithText = new Dictionary<string, string>();
while(myReader.Read())
{
    string buttonText = myReader["client"].ToString();
    string buttonId = myReader["ID"].ToString();
    buttonIdsWithText.Add(buttonId, buttonText);
}
lv1.DataSource = buttonIdsWithText;
lv1.DataBind();

public void lv1_ItemDataBound(object sender, ListViewItemEventArgs e)
{
    if (e.Item.ItemType != ListViewItemType.DataItem)
    {
        return;
    }

    KeyValuePair<string, string> idWithText =
        (KeyValuePair<string, string>)e.Item.DataItem;
    Button myButton = e.Item.FindControl("btn1") as Button;
    myButton.Text = idWithText.Value;
}