Cell border style is lost when exporting to excel using insert command

Hello All,

I am trying to export to excel using insert command. All operations are working fine but when I export to excel, the excel file cell style is changed automatically to Bold for example. If I use column by column insertion, then no issue for cell style.

I want my default cell style while export operation. How can I solve this issue.

Please help to solve this issue.

For more information, I am providing my code and exported excel file image

.

private void button5_Click_1(object sender, RoutedEventArgs e)
        {
            string templatePath = System.IO.Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "Acty System\\Templates\\Employess1.xls");
            string directoryPath = System.IO.Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "Acty System\\Test\\test.xls");
            string excelConnectionString = string.Format(CultureInfo.InvariantCulture, "Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties=\"HDR=YES;\";Jet OLEDB:Engine Type=37", directoryPath);
            OleDbCommand command = new OleDbCommand();
            OleDbConnection connection = new OleDbConnection(excelConnectionString);
            try
            {
                //Copy from excel template and create a new excel file in selected location
                Microsoft.Office.Interop.Excel.Application excel = new Microsoft.Office.Interop.Excel.Application();
                excel.Interactive = false;
                Microsoft.Office.Interop.Excel.Workbook workBook = null;
                excel.Visible = false;
                workBook = excel.Workbooks.Open(templatePath, Type.Missing);
                workBook.SaveCopyAs(directoryPath); //// 97-2003 xls format

                //Fetch records
                var query = this.dc.Employees.Select(p => new { p.FirstName, p.LastName, p.EmployeeID }).AsEnumerable();
                connection.Open();
                string commandString = string.Empty;
                command = new OleDbCommand(commandString, connection);
                foreach (var item in dc.Employees)
                {
                    commandString = "Insert into [PurchaseInvHD$] (FirstName,LastName,EmployeeID) values('" + item.FirstName + "','" + item.LastName + "','" + item.EmployeeID + "')";
                    command.CommandText = commandString;
                    command.ExecuteNonQuery();
                }

                connection.Close();
                MessageBox.Show("Expprted");
            }
            catch
            {
                connection.Close();
                MessageBox.Show("Error");
            }
        }

Regards, Ranjith T Rajan Acty System India Pvt Ltd.