How to Download Database to Excel Sheet in C#.NET

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Data.OleDb;
using ExcelLibrary.SpreadSheet;
using Excel = Microsoft.Office.Interop.Excel;
using Microsoft.Office.Interop.Excel;
namespace ClientManagementApp
{
    public partial class FrmReport: Form
    {
        DataSet dstResults = new DataSet();
        DataView myView;
        DataSet dstConverted = new DataSet();
        DataSet dstKeyData = new DataSet();
        DataView myConvertedView;
        DataView myKeyDataView;
        DataSet dataSet = null;
        public FrmReport()
        {
            InitializeComponent();
            BindDataGrid();
        }
        private void BindDataGrid()
        {
            // DataTable dt = new DataTable();
            System.Data.DataTable dtConverted = DataGridView2DataTable(dataGridView1, "Converted");
            System.Data.DataTable dtKeyData = DataGridView2DataTable(dataGridView2, "KeyData");
            dataGridView1.DataSource = dtConverted;
            dataGridView2.DataSource = dtKeyData;
            // dgvResults.DataSource = dt;
        }
        public System.Data.DataTable DataGridView2DataTable(DataGridView dgv, String tblName, int minRow = 0)
        {
            System.Data.DataTable dt = new System.Data.DataTable(tblName);
            // Header columns
            foreach(DataGridViewColumn column in dgv.Columns)
            {
                DataColumn dc = new DataColumn(column.Name.ToString());
                dt.Columns.Add(dc);
            }
            // Data cells
            for (int i = 0; i < dgv.Rows.Count; i++)
            {
                DataGridViewRow row = dgv.Rows[i];
                DataRow dr = dt.NewRow();
                for (int j = 0; j < dgv.Columns.Count; j++)
                {
                    dr[j] = (row.Cells[j].Value == null) ? "" : row.Cells[j].Value.ToString();
                }
                dt.Rows.Add(dr);
            }
            // Related to the bug arround min size when using ExcelLibrary for export
            for (int i = dgv.Rows.Count; i < minRow; i++)
            {
                DataRow dr = dt.NewRow();
                for (int j = 0; j < dt.Columns.Count; j++)
                {
                    dr[j] = " ";
                }
                dt.Rows.Add(dr);
            }
            return dt;
        }
        Excel.Application ExcelApp;
        private void Btngenerate_Click(object sender, EventArgs e)
        {
            int maxs = 1;
            FileName: int max = 0;
            progressBar1.Minimum = 0;
            ++max;
            progressBar1.Maximum = max;
            progressBar1.Visible = true;
            lbl_wait.Visible = true;
            // Create a DataSet and put both tables in it.
            System.Data.DataTable dtConverted = DataGridView2DataTable(dataGridView1, "Converted");
            System.Data.DataTable dtKeyData = DataGridView2DataTable(dataGridView2, "KeyData");
            dataSet = new DataSet("General");
            dataSet.Tables.Add(dtConverted);
            dataSet.Tables.Add(dtKeyData);
            try
            {
                ExcelApp = new Excel.Application();
                Microsoft.Office.Interop.Excel.Workbook xlWorkbook = ExcelApp.Workbooks.Add(Microsoft.Office.Interop.Excel.XlWBATemplate.xlWBATWorksheet);
                // Loop over DataTables in DataSet.
                DataTableCollection collection = dataSet.Tables;
                for (int i = collection.Count; i > 0; i--)
                {
                    Sheets xlSheets = null;
                    Microsoft.Office.Interop.Excel.Worksheet xlWorksheet = null;
                    //xlWorksheet.Name = "Mandate Summary";
                    //Create Excel Sheets
                    xlSheets = ExcelApp.Sheets;
                    xlWorksheet = (Microsoft.Office.Interop.Excel.Worksheet) xlSheets.Add(xlSheets[1],
                    Type.Missing, Type.Missing, Type.Missing);
                    System.Data.DataTable table = collection[i - 1];
                    xlWorksheet.Name = table.TableName;
                    for (int j = 1; j < table.Columns.Count + 1; j++)
                    {
                        ExcelApp.Cells[1, j] = table.Columns[j - 1].ColumnName;
                    }
                    // Storing Each row and column value to excel sheet
                    for (int k = 0; k < table.Rows.Count; k++)
                    {
                        for (int l = 0; l < table.Columns.Count; l++) {
                            ExcelApp.Cells[k + 2, l + 1] = table.Rows[k].ItemArray[l].ToString();
                        }
                    }
                    ExcelApp.Columns.AutoFit();
                }
                ((Microsoft.Office.Interop.Excel.Worksheet) ExcelApp.ActiveWorkbook.Sheets[ExcelApp.ActiveWorkbook.Sheets.Count]).Delete();
                ExcelApp.Visible = true;
                //xlWorkbook.SaveAs("D:\\ClientData.xls");
                xlWorkbook.SaveAs(@
                "D:\ClientData-CR-DR-ALL-" + DateTime.Now.ToString("ddMMyyyy") + "-INP-" + maxs.ToString().PadLeft(6, '0') + ".xls");
                lblreport.Text = "Report Generate Successfully";
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }++maxs;
            progressBar1.Value++;
            // goto FileName;
        }
        private void FrmReport_Load(object sender, EventArgs e)
        {
            //ReadData("SELECT ID,BankName,ContactPersonName,ContactNumber,EmailId,PORecieved,PayementRecievedDate,Remark,EToken,DigitalCertificate FROM tbl_ClientDetails",
            ReadData("SELECT ID,NAME,AMT,AMC_INC,AMC,PAYMENT_RECVD,PayementRecievedDate,NARAT,VAT,S_T FROM tbl_ClientDetails",
            ref dstConverted, "Converted");
            myConvertedView = ((System.Data.DataTable) dstConverted.Tables["Converted"]).DefaultView;
            ReadData("Select ID,NAME,AMT,W_E_F,PAYMENT_RECVD_vat,DSC_2,DSC_3 from tbl_ClientDetails", ref dstKeyData, "KeyData");
            myKeyDataView = ((System.Data.DataTable) dstKeyData.Tables["KeyData"]).DefaultView;
            dataGridView1.DataSource = myConvertedView;
            dataGridView2.DataSource = myKeyDataView;
            // dataGridView1.Refresh();
        }
        public void ReadData(string strSQL, ref DataSet dstMain, string strTableName = "default")
        {
            try
            {
                string connectionString = @
                " Provider=Microsoft.ACE.OLEDB.12.0;Data Source=ClientMgmtDb1.accdb;";
                // OleDbConnection cnn = conection();
                OleDbConnection cnn = new OleDbConnection(connectionString);
                OleDbCommand cmd = new OleDbCommand(strSQL, cnn);
                cnn.Open();
                OleDbDataAdapter da = new OleDbDataAdapter(cmd);
                da.Fill(dstMain, strTableName);
                da.Dispose();
                cnn.Close();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
        }
    }
}