Binding DropDown List

private void BindDropDown()
    {
        using (SqlConnection con = new SqlConnection(@"Data Source=maj-056\sqlexpress;Initial Catalog=Sample;Integrated Security=True;Pooling=False"))
        {
            SqlCommand cmd = new SqlCommand("sp_select", con);
            cmd.CommandType = CommandType.StoredProcedure;
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds);
            if (ds.Tables[0].Rows.Count > 0)
            {
                DropDownList1.DataSource = ds.Tables[0];
                DropDownList1.DataTextField = "";
                DropDownList1.DataValueField = "";
                DropDownList1.DataBind();

                DropDownList2.DataSource = ds.Tables[1];
                DropDownList2.DataTextField = "";
                DropDownList2.DataValueField = "";
                DropDownList2.DataBind();

                DropDownList3.DataSource = ds.Tables[2];
                DropDownList3.DataTextField = "";
                DropDownList3.DataValueField = "";
                DropDownList3.DataBind();
            }
        }
    }

create proc sp_select
as
begin
select * from Table1
end
begin
select * from Table2
end
begin
select * from Table3
end