Generic Method to Bind ASP.Net DropDownList with DataTable or DataSet

This way

    private DataSet GetData(string query)
    {
        string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        SqlCommand cmd = new SqlCommand(query);
        using (SqlConnection con = new SqlConnection(conString))
        {
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                cmd.Connection = con;
                sda.SelectCommand = cmd;
                using (DataSet ds = new DataSet())
                {
                    sda.Fill(ds);
                    return ds;
                }
            }
        }
    }
    private void BindDropDownList(DataSet ds, DropDownList ddl, string textField, string valueField)
    {
        ddl.Items.Clear();
        ddl.AppendDataBoundItems = true;
        ddl.DataSource = ds;
        ddl.DataTextField = textField;
        ddl.DataTextField = valueField;
        ddl.DataBind();
    }

To call

        DataSet ds =  this.GetData("select * from countries");
        this.BindDropDownList(ds, DropDownList1, "CountryName", "CountryId");