Gridview inside Gridview in ASP.NET C#

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class NestedGridview : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            loadAll();
        }
    }

    private void loadAll()
    {
        DataSet ds = new DataSet();
        ds = query.selectAll();
        //DataSet ds1 = new DataSet();
        //ds1 = query.selectAll();
        //ds1.Merge(ds);

        //  DataTable dt = new DataTable();
        // dt = query.selectAllTBL();
        GridView1.DataSource = ds;
        GridView1.DataBind();
    }
    protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
    {
        GridView1.EditIndex = -1;
        loadAll();
    }
    protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {

    }
    protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
    {
        GridView1.EditIndex = e.NewEditIndex;
        loadAll();

    }
    protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        GridViewRow row = (GridViewRow)GridView1.Rows[e.RowIndex];
        string lblID = ((Label)row.FindControl("lblID")).Text;
        string txt = ((TextBox)row.FindControl("txt")).Text;
        GridView1.EditIndex = -1;
        int n = Class1.nonquery1(lblID, txt);
        loadAll();
        // int n = query.update(lblID, txt);
        //if (n == 0)
        //{

        //}
    }
    protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
    {
        if (e.CommandName == "Show")
        {
            int RowIndex = Convert.ToInt32((e.CommandArgument).ToString());
            Button btn = (Button)GridView1.Rows[RowIndex].FindControl("btnShow");
           // Label lblID = (Label)GridView1.Rows[RowIndex - 1].FindControl("Label1");
           // int row = Convert.ToInt32(lblID.Text);
            if (btn.Text == "Expand")
            {

                //  Label lblID = (Label)gvDiscMaster.Rows[RowIndex].FindControl("lblID");
                GridView gv = (GridView)GridView1.Rows[RowIndex ].FindControl("GridView2");

                long id = long.Parse(((Label)GridView1.Rows[RowIndex].FindControl("lblID")).Text);
                DataSet ds1 = new DataSet();
                ds1 = query.selectwithId(id);
                gv.DataSource = ds1;
                gv.DataBind();
                btn.Text = "Collapse";
            }
            else if (btn.Text == "Collapse")
            {
                GridView gv = (GridView)GridView1.Rows[RowIndex].FindControl("GridView2");

                long id = long.Parse(e.CommandArgument.ToString());
                //DataSet ds1 = new DataSet();
               // ds1 = query.selectwithId(id);
                gv.DataSource = null;
                gv.DataBind();
                btn.Text = "Expand";
            }

        }
    }
}