Creating csv file and editable dropdown with xml saving

 <?xml version="1.0" encoding="us-ascii" standalone="yes"?>
<Masters>

 <DESIGNATION>
    <DISG>Additional Inspector General  A/C</DISG>  
  </DESIGNATION>
</Masters>



using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Globalization;
using System.Text.RegularExpressions;
using System.Xml;
using System.IO;
using System.Reflection;
using System.Net.NetworkInformation;
using System.Management;
  public partial class A: Form
  {
        string sourcefile = Application.StartupPath + "\\Master.xml";
         int cmbDDODesignationflag = 0;

           private void A_Load(object sender, EventArgs e)
        {

                   loadmasters();

        }

         public void loadmasters()
        {
            #region : XML Parsing to load all ComboBox fields :
            try
            {

               // address();
                XmlDocument doc = new XmlDocument();
                doc.Load(sourcefile);
                         
                XmlNodeList DDODISGNode = doc.GetElementsByTagName("DISG");
                foreach (XmlNode Node3Node in DDODISGNode)
                {
                    //These nodes contain the data we want so lets add it to our List.
                    cmbDDODesignation.Items.Add(Node3Node.InnerText.ToString().Trim());
                }             

            }
            catch (Exception ex)
            {
                Logging.Logflatfile_Ex(ex);
            }

            #endregion
        }

    public void updatemasters()
        {
            try
            {
                //FileStream fxml = new FileStream(sourcefile, FileMode.OpenOrCreate);
                XmlDocument xDoc = new XmlDocument();
                xDoc.Load(sourcefile);

                if (cmbDDODesignationflag == 1)
                {

                    // find channel element to append to
                    var channels = xDoc.GetElementsByTagName("DESIGNATION", string.Empty);

                    // if no channel tags then exit
                    if (channels.Count == 0)
                        return;
                    // create new item
                    var newItem = xDoc.CreateElement("DISG");
                    // add attributes (with value)
                    // Note: You do not have any attributes in your xml.
                    // This is added to show you how to do it and what the effect is.

                    newItem.InnerText = cmbDDODesignation.Text.ToString().Trim();

                    channels[0].AppendChild(newItem);
                    // add new item to first channel         
                    xDoc.Save(sourcefile);
                    cmbDDODesignation.Items.Add(cmbDDODesignation.Text.ToString().Trim());
                }
               
                          }
            catch (Exception ex)
            {
                MessageBox.Show("Exception Occurred.", "Exception", MessageBoxButtons.OK, MessageBoxIcon.Error);
                Logging.Logflatfile_Ex(ex);
            }

        }

     private void cmbDDODesignation_Leave(object sender, EventArgs e)
        {
            string cmbDDODesignationNewItem = string.Empty;
            cmbDDODesignationNewItem = this.cmbDDODesignation.Text.ToString().Trim();

            // If there is no flavor to add, do nothing
            if (cmbDDODesignationNewItem == string.Empty)
            {
                cmbDDODesignationflag = 0;
                return;
            }
            else
            {
                if (this.cmbDDODesignation.FindStringExact(cmbDDODesignationNewItem) != -1)
                {
                   
                //if (cmbDDODesignation.Items.Contains(cmbDDODesignationNewItem.ToUpper()) || cmbDDODesignation.Items.Contains(cmbDDODesignationNewItem.ToLower()))
                // {
                    //MessageBox.Show(NewItem + " exists already in the list and will not be added.");
                    cmbDDODesignationflag = 0;
                    return;
                }
                else
                {
                    //this.cmbDDODesignation.Items.Add(cmbDDODesignationNewItem);
                    cmbDDODesignationflag = 1;

                }

            }

          
        }

public void createCSVFromDatable()
        {
            try
            {
                DataTable dt = new DataTable();
                #region : Assigning Fields data to DataTable :

             
                                                   
                dt.Columns.Add("DDODisgnation");
                 dt.Columns.Add("DateTime");            



                                DataRow dr = dt.NewRow();

              
                             
                dr["DDODisgnation"] = cmbDDODesignation.Text.Trim();
                   dr["DateTime"] = DateTime.Now.ToString();
             




                          

              
                dt.Rows.Add(dr);
                #endregion
                destcsvfile = Application.StartupPath + "\\A.csv";
                string newFileName = destcsvfile;


                string clientDetails =     dr["DDODisgnation"].ToString().Trim() + ","             
                                     
                                      + dr["DateTime"].ToString().Trim() + Environment.NewLine;


                if (!File.Exists(newFileName))
                {
                    string clientHeader =  "DDODisgnation".Trim() + ","                                                       
                                        + "DateTime".Trim() + Environment.NewLine;

                    File.WriteAllText(newFileName, clientHeader);
                    File.AppendAllText(newFileName, clientDetails);

                }
                else
                {
                    File.AppendAllText(newFileName, clientDetails);
                }

                if (File.Exists(destcsvfile))
                {
                    MessageBox.Show("Record Created Sucessfully for " + txtFirstName.Text + "\n with Unique ID: " + dr["UniqueID"], "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
                                        updatemasters();

                }
                else
                {
                    MessageBox.Show("Unable to create csv file", "Fail", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show("Exception Occurred.", "Exception", MessageBoxButtons.OK, MessageBoxIcon.Error);
                Logging.Logflatfile_Ex(ex);
            }

        }