Datatable Values in Excel Report

protected void btnreport_Click(object sender, EventArgs e)
    {
        try
        {
            bind();
            DataView dv = new DataView(dtt);
         
            System.Text.StringBuilder builder = new System.Text.StringBuilder();
            System.Data.DataTable dt = dv.Table;
            string headerToExport = string.Empty;
            foreach (DataColumn col in dt.Columns)              
               
                headerToExport += (char)34 + col.ColumnName + (char)34 + (char)44;
            headerToExport.Remove(headerToExport.Length - 1, 1);
            headerToExport = headerToExport + Environment.NewLine + Environment.NewLine;
            builder.Append(headerToExport);
            string body = string.Empty;
            foreach (DataRow row in dt.Rows)
            {
                foreach (object obj in row.ItemArray)
                    body += (char)34 + obj.ToString() + (char)34 + (char)44;
                body.Remove(body.Length - 1, 1);
                body = body + Environment.NewLine;
            }
            builder.Append(body);
            builder.Append(Environment.NewLine);
            builder.Append(Environment.NewLine);
            Response.ContentType = "application/vnd.ms-excel";
            Response.AddHeader("content-disposition", "attachment;filename=Report.csv");
            Response.Charset = "";
            Response.Write(builder.ToString());
            Response.Flush();
            Response.End();
        }
        catch (Exception ex)
        {
            Response.Write(ex.Message);
        }
        finally { }
    }
}

You Can Also Use This Code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using MySql.Data.MySqlClient;
using System.Data;

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

            Bind();
        }
    }
    protected void BtnGenerateExcel_Click(object sender, EventArgs e)
    {
        try
        {
            Bind();
            ExportToExcel((DataTable)ViewState["Datatable"]);
         
        }
        catch (Exception ex)
        {
            Response.Write(ex.Message);
        }
        finally {
            ViewState["Datatable"] = null;
        }
    }
    public void ExportToExcel(DataTable dt)
    {
        if (dt.Rows.Count > 0)
        {
            string filename = "Test.xls";
            System.IO.StringWriter tw = new System.IO.StringWriter();
            System.Web.UI.HtmlTextWriter hw = new System.Web.UI.HtmlTextWriter(tw);
            DataGrid dgGrid = new DataGrid();
            dgGrid.DataSource = dt;
            dgGrid.DataBind();

            //Get the HTML for the control.
            dgGrid.RenderControl(hw);
            //Write the HTML back to the browser.
            Response.ContentType = "application/vnd.ms-excel";
            Response.AppendHeader("Content-Disposition", "attachment; filename=" + filename + "");
            this.EnableViewState = false;
            Response.Write(tw.ToString());
            Response.End();
        }
    }

    public void Bind()
    {
        using (MySqlConnection ObjCon = new MySqlConnection(new CommonClass().GetConnectionString()))
        {
            try
            {
                DataSet ds = new DataSet();
                MySqlDataAdapter ada = new MySqlDataAdapter("Select * from CustomerOrder", ObjCon);
                ada.Fill(ds);
                DataTable dt = new DataTable();
                dt.Columns.Add("Cus_orderId");
                dt.Columns.Add("Fund_TransId");
                dt.Columns.Add("BeneName");
                dt.Columns.Add("BeneAcc");
                dt.Columns.Add("Bank");
                dt.Columns.Add("Branch");
                dt.Columns.Add("Amount");
             
                for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
                {
                    DataRow dr = dt.NewRow();
                    dt.Rows.Add(dr);
                    DataTable dt1 = new DataTable();
                    MySqlDataAdapter ad1 = new MySqlDataAdapter("SELECT Name,AccountNo,BankName,BranchName FROM Beneficiary Where Id='"+ds.Tables[0].Rows[0][3].ToString()+"'", ObjCon);
                    ad1.Fill(dt1);
                    dr[0] = ds.Tables[0].Rows[i][0].ToString();
                    dr[1] = ds.Tables[0].Rows[i][1].ToString();
                    dr[2] = dt1.Rows[0][0].ToString();
                    dr[3] = dt1.Rows[0][1].ToString();
                    dr[4] = dt1.Rows[0][2].ToString();
                    dr[5] = dt1.Rows[0][3].ToString();
                    dr[6] = ds.Tables[0].Rows[i][6].ToString();
                }
                GridView1.DataSource = dt;
                ViewState["Datatable"] = dt;
                GridView1.DataBind();
            }

            catch (Exception ex)
            {
                Response.Write(ex.Message);
            }
        }

    }
}