How to export searched or filtered records in GridView to Excel in ASP.Net

I got the code for it and it is done

    protected void btnExcel_Click(object sender, EventArgs e)
    {
        if (btnsearch1.Text == "Search")
        {
            conn.Open();
            qry = "SELECT * FROM PDC_Master WHERE Receipt_No LIKE '%'+@recno+'%' AND Date LIKE '%' + @recdate + '%' AND Edxel_Enroll_No LIKE '%' + @enroll + '%' AND Stud_Name LIKE '%' + @stud + '%' AND University LIKE '%' + @uni + '%' AND Course LIKE '%' + @course + '%' AND Pay_Mode LIKE '%' + @paymode + '%' AND Cheque_Date LIKE '%' + @chequedate + '%' AND Bank_Name LIKE '%' + @bank + '%'";

            //qry = "Select * from Service_Provider where S_Provider_Id Like @sproid and S_Provider_Name Like @sproname and Contact_Person Like @person and City Like @city and State Like @state and Mobile_No Like @mob ";

            SqlCommand cmd = new SqlCommand(qry, conn);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            cmd.Parameters.AddWithValue("@recno", this.txtrecno.Text.Trim());
            cmd.Parameters.AddWithValue("@recdate", this.txtrecdate.Text.Trim());
            cmd.Parameters.AddWithValue("@stud", this.txtstudsearch.Text.Trim());
            cmd.Parameters.AddWithValue("@course", this.ddlcoursesearch.SelectedValue.Trim());
            cmd.Parameters.AddWithValue("@uni", this.ddlunisearch.SelectedValue.Trim());
            cmd.Parameters.AddWithValue("@paymode", this.txtpaymode.Text.Trim());
            cmd.Parameters.AddWithValue("@bank", this.txtbank.Text.Trim());
            cmd.Parameters.AddWithValue("@chequedate", this.txtchequedate.Text.Trim());
            cmd.Parameters.AddWithValue("@enroll", this.txtenrollno.Text.Trim());
            DataTable ds = new DataTable();
            da.Fill(ds);
            this.GridView1.DataSource = ds;
            this.GridView1.DataBind();
            GridView1.HeaderRow.Cells[0].Visible = false;
            GridView1.HeaderRow.Cells[1].Visible = false;
            GridView1.HeaderRow.Cells[2].Visible = false;

            GridView1.Columns[0].Visible = false;
            GridView1.Columns[1].Visible = false;
            GridView1.Columns[2].Visible = false;
            string filename = "PDC_Data.xls";
            System.IO.StringWriter tw = new System.IO.StringWriter();
            System.Web.UI.HtmlTextWriter hw = new System.Web.UI.HtmlTextWriter(tw);
            DataGrid dgGrid = new DataGrid();
            GridView1.DataSource = ds;
            GridView1.AllowPaging = false;
            GridView1.DataBind();


            GridView1.RenderControl(hw);

            Response.ContentType = "application/vnd.ms-excel";
            Response.AppendHeader("Content-Disposition", "attachment; filename=" + filename + "");
            this.EnableViewState = false;
            Response.Write(tw.ToString());
            Response.End();


            conn.Close();
        }
        else
        {
            Response.ClearContent();
            Response.Buffer = true;
            Response.AddHeader("content-disposition", string.Format("attachment; filename={0}", "PDC_Data.xlsx"));
            Response.ContentType = "application/ms-excel";
            StringWriter sw = new StringWriter();
            HtmlTextWriter htw = new HtmlTextWriter(sw);


            GridView1.AllowPaging = false;
            BindDetails();
            GridView1.HeaderRow.Cells[0].Visible = false;
            GridView1.HeaderRow.Cells[1].Visible = false;
            GridView1.HeaderRow.Cells[2].Visible = false;

            GridView1.Columns[0].Visible = false;
            GridView1.Columns[1].Visible = false;
            GridView1.Columns[2].Visible = false;
            //BindDetails();
            //Change the Header Row back to white color
            GridView1.HeaderRow.Style.Add("background-color", "#FFFFFF");
            //Applying stlye to gridview header cells
            for (int i = 0; i < GridView1.HeaderRow.Cells.Count; i++)
            {
                GridView1.HeaderRow.Cells[i].Style.Add("background-color", "#df5015");

            }
            GridView1.RenderControl(htw);

            Response.Write(sw.ToString());
            Response.End();
        }

       


    }