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How to create CSV File Uploader in Desktop Application

Introduction

This blog is useful for uploading a CSV file in desktop application(C#) and store data in MS-Access Database. Also you can modify connection string and query useful for stored data in SQL Server.

Using The Code

Step 1: Create a class to upload CSV file. 

CSVUpload.cs

  1. using System.IO;  
  2. using System.Text.RegularExpressions;  
  3. using System.Data;  
  4. public sealed class CsvReader: System.IDisposable {  
  5.     public CsvReader(string fileName): this(new FileStream(fileName, FileMode.Open, FileAccess.Read)) {}  
  6.     public CsvReader(Stream stream) {  
  7.         __reader = new StreamReader(stream);  
  8.     }  
  9.     public DataSet RowEnumerator {  
  10.         get {  
  11.             if (null == __reader) throw new System.ApplicationException("I can't start reading without CSV input.");  
  12.             __rowno = 0;  
  13.             string sLine;  
  14.             string sNextLine;  
  15.             DataSet ds = new DataSet();  
  16.             DataTable dt = ds.Tables.Add("TheData");  
  17.             while (null != (sLine = __reader.ReadLine())) {  
  18.                 while (rexRunOnLine.IsMatch(sLine) && null != (sNextLine = __reader.ReadLine()))  
  19.                 sLine += "\n" + sNextLine;  
  20.                 __rowno++;  
  21.                 DataRow dr = dt.NewRow();  
  22.                 string[] values = rexCsvSplitter.Split(sLine);  
  23.                 for (int i = 0; i < values.Length; i++) {  
  24.                     values[i] = Csv.Unescape(values[i]);  
  25.                     if (__rowno == 1) {  
  26.                         dt.Columns.Add(values[i].Trim());  
  27.                     } else {  
  28.                         if (Csv.CharNotAllowes(values[i])) {  
  29.                             dr[i] = values[i].Trim();  
  30.                         }  
  31.                     }  
  32.                 }  
  33.                 if (__rowno != 1) {  
  34.                     dt.Rows.Add(dr);  
  35.                 }  
  36.                 //yield return values;  
  37.             }  
  38.             __reader.Close();  
  39.             return ds;  
  40.         }  
  41.     }  
  42.     public long RowIndex {  
  43.         get {  
  44.             return __rowno;  
  45.         }  
  46.     }  
  47.     public void Dispose() {  
  48.         if (null != __reader) __reader.Dispose();  
  49.     }  
  50.     //============================================  
  51.     private long __rowno = 0;  
  52.     private TextReader __reader;  
  53.     private static Regex rexCsvSplitter = new Regex(@  
  54.     ",(?=(?:[^"  
  55.     "]*"  
  56.     "[^"  
  57.     "]*"  
  58.     ")*(?![^"  
  59.     "]*"  
  60.     "))");  
  61.     private static Regex rexRunOnLine = new Regex(@  
  62.     "^[^"  
  63.     "]*(?:"  
  64.     "[^"  
  65.     "]*"  
  66.     "[^"  
  67.     "]*)*"  
  68.     "[^"  
  69.     "]*$");  
  70. }  
  71. public static class Csv {  
  72.     public static string Escape(string s) {  
  73.         if (s.Contains(QUOTE)) s = s.Replace(QUOTE, ESCAPED_QUOTE);  
  74.         if (s.IndexOfAny(CHARACTERS_THAT_MUST_BE_QUOTED) > -1) s = QUOTE + s + QUOTE;  
  75.         return s;  
  76.     }  
  77.     public static string Unescape(string s) {  
  78.         if (s.StartsWith(QUOTE) && s.EndsWith(QUOTE)) {  
  79.             s = s.Substring(1, s.Length - 2);  
  80.             if (s.Contains(ESCAPED_QUOTE)) s = s.Replace(ESCAPED_QUOTE, QUOTE);  
  81.         }  
  82.         return s;  
  83.     }  
  84.     public static bool CharNotAllowes(string s) {  
  85.         if (s.IndexOfAny(CHARACTERS_THAT_NOT_ALLOWED) > -1) {  
  86.             return false;  
  87.         } else {  
  88.             return true;  
  89.         }  
  90.     }  
  91.     private const string QUOTE = "\"";  
  92.     private const string ESCAPED_QUOTE = "\"\"";  
  93.     private static char[] CHARACTERS_THAT_MUST_BE_QUOTED = {  
  94.         ',', '"', '\n'  
  95.     };  
  96.     private static char[] CHARACTERS_THAT_NOT_ALLOWED = {  
  97.         '?', '!', '^', '*', '~', 'Ñ', '½', 'Ð', '', '»', 'µ', 'º', 'Ñ', '´'  
  98.     };  
  99. }
Step 2: Create Design


Figure 1: CSV Reader

Step 3: Write Code
  1. using System;  
  2. using System.Drawing;  
  3. using System.Collections;  
  4. using System.ComponentModel;  
  5. using System.Windows.Forms;  
  6. using System.Data;  
  7. using System.Data.SqlClient;  
  8. using System.Data.Odbc;  
  9. using System.IO;  
  10. using System.Data.OleDb;  
  11. namespace Upload_Stock_Data {  
  12.     /// <summary>  
  13.     /// Summary description for frmMain.  
  14.     /// </summary>  
  15.     public class frmMain: System.Windows.Forms.Form   
  16.     {  
  17.         #region Declarations  
  18.         private System.Windows.Forms.GroupBox gbMain;  
  19.         private System.Windows.Forms.TextBox txtCSVFolderPath;  
  20.         private System.Windows.Forms.Button btnOpenFldrBwsr;  
  21.         private System.Windows.Forms.FolderBrowserDialog fbdCSVFolder;  
  22.         private System.Windows.Forms.TextBox txtCSVFilePath;  
  23.         private System.Windows.Forms.Button btnOpenFileDlg;  
  24.         private System.Windows.Forms.OpenFileDialog openFileDialogCSVFilePath;  
  25.         private System.Windows.Forms.Button btnImport;  
  26.         private System.Windows.Forms.DataGrid dGridCSVdata;  
  27.         string strCSVFile = "";  
  28.         private System.Windows.Forms.GroupBox gbMainUploadData;  
  29.         private System.Windows.Forms.Button btnUpload;  
  30.         System.Data.Odbc.OdbcDataAdapter obj_oledb_da;  
  31.         private bool bolColName = true;  
  32.         string strFormat = "CSVDelimited";  
  33.         private System.Windows.Forms.Label lblFolderPath;  
  34.         private System.Windows.Forms.Label lblFilePath;  
  35.         /// <summary>  
  36.         /// Required designer variable.  
  37.         /// </summary>  
  38.         private System.ComponentModel.Container components = null;#endregion  
  39.         #region Constructor  
  40.         public frmMain() {  
  41.             //  
  42.             // Required for Windows Form Designer support  
  43.             //  
  44.             InitializeComponent();  
  45.   
  46.             //  
  47.             // TODO: Add any constructor code after InitializeComponent call  
  48.             //  
  49.         }#endregion  
  50.         #region Destructor  
  51.         /// <summary>  
  52.         /// Clean up any resources being used.  
  53.         /// </summary>  
  54.         protected override void Dispose(bool disposing) {  
  55.             if (disposing) {  
  56.                 if (components != null) {  
  57.                     components.Dispose();  
  58.                 }  
  59.             }  
  60.             base.Dispose(disposing);  
  61.         }  
  62.         #endregion  
  63.         #region Windows Form Designer generated code  
  64.         /// <summary>  
  65.         /// Required method for Designer support - do not modify  
  66.         /// the contents of this method with the code editor.  
  67.         /// </summary>  
  68.         private void InitializeComponent() {  
  69.             this.gbMain = new System.Windows.Forms.GroupBox();  
  70.             this.lblFilePath = new System.Windows.Forms.Label();  
  71.             this.lblFolderPath = new System.Windows.Forms.Label();  
  72.             this.dGridCSVdata = new System.Windows.Forms.DataGrid();  
  73.             this.btnImport = new System.Windows.Forms.Button();  
  74.             this.btnOpenFileDlg = new System.Windows.Forms.Button();  
  75.             this.txtCSVFilePath = new System.Windows.Forms.TextBox();  
  76.             this.btnOpenFldrBwsr = new System.Windows.Forms.Button();  
  77.             this.txtCSVFolderPath = new System.Windows.Forms.TextBox();  
  78.             this.fbdCSVFolder = new System.Windows.Forms.FolderBrowserDialog();  
  79.             this.openFileDialogCSVFilePath = new System.Windows.Forms.OpenFileDialog();  
  80.             this.gbMainUploadData = new System.Windows.Forms.GroupBox();  
  81.             this.btnUpload = new System.Windows.Forms.Button();  
  82.             this.gbMain.SuspendLayout();  
  83.             ((System.ComponentModel.ISupportInitialize)(this.dGridCSVdata)).BeginInit();  
  84.             this.gbMainUploadData.SuspendLayout();  
  85.             this.SuspendLayout();  
  86.             //   
  87.             // gbMain  
  88.             //   
  89.             this.gbMain.BackColor = System.Drawing.SystemColors.InactiveCaptionText;  
  90.             this.gbMain.Controls.Add(this.lblFilePath);  
  91.             this.gbMain.Controls.Add(this.lblFolderPath);  
  92.             this.gbMain.Controls.Add(this.dGridCSVdata);  
  93.             this.gbMain.Controls.Add(this.btnImport);  
  94.             this.gbMain.Controls.Add(this.btnOpenFileDlg);  
  95.             this.gbMain.Controls.Add(this.txtCSVFilePath);  
  96.             this.gbMain.Controls.Add(this.btnOpenFldrBwsr);  
  97.             this.gbMain.Controls.Add(this.txtCSVFolderPath);  
  98.             this.gbMain.FlatStyle = System.Windows.Forms.FlatStyle.System;  
  99.             this.gbMain.Location = new System.Drawing.Point(16, 8);  
  100.             this.gbMain.Name = "gbMain";  
  101.             this.gbMain.Size = new System.Drawing.Size(504, 416);  
  102.             this.gbMain.TabIndex = 0;  
  103.             this.gbMain.TabStop = false;  
  104.             this.gbMain.Text = "Import CSV Data";  
  105.             //   
  106.             // lblFilePath  
  107.             //   
  108.             this.lblFilePath.Location = new System.Drawing.Point(32, 47);  
  109.             this.lblFilePath.Name = "lblFilePath";  
  110.             this.lblFilePath.Size = new System.Drawing.Size(72, 20);  
  111.             this.lblFilePath.TabIndex = 12;  
  112.             this.lblFilePath.Text = "File Path:";  
  113.             this.lblFilePath.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;  
  114.             //   
  115.             // lblFolderPath  
  116.             //   
  117.             this.lblFolderPath.Location = new System.Drawing.Point(32, 23);  
  118.             this.lblFolderPath.Name = "lblFolderPath";  
  119.             this.lblFolderPath.Size = new System.Drawing.Size(72, 20);  
  120.             this.lblFolderPath.TabIndex = 11;  
  121.             this.lblFolderPath.Text = "Folder Path:";  
  122.             this.lblFolderPath.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;  
  123.             //   
  124.             // dGridCSVdata  
  125.             //   
  126.             this.dGridCSVdata.AlternatingBackColor = System.Drawing.SystemColors.ControlLightLight;  
  127.             this.dGridCSVdata.CaptionForeColor = System.Drawing.Color.AliceBlue;  
  128.             this.dGridCSVdata.CaptionText = "Imported CSV Data";  
  129.             this.dGridCSVdata.DataMember = "";  
  130.             this.dGridCSVdata.ForeColor = System.Drawing.Color.YellowGreen;  
  131.             this.dGridCSVdata.HeaderBackColor = System.Drawing.Color.BlanchedAlmond;  
  132.             this.dGridCSVdata.HeaderForeColor = System.Drawing.Color.Black;  
  133.             this.dGridCSVdata.Location = new System.Drawing.Point(8, 124);  
  134.             this.dGridCSVdata.Name = "dGridCSVdata";  
  135.             this.dGridCSVdata.ParentRowsForeColor = System.Drawing.Color.Yellow;  
  136.             this.dGridCSVdata.ReadOnly = true;  
  137.             this.dGridCSVdata.SelectionForeColor = System.Drawing.SystemColors.ControlLight;  
  138.             this.dGridCSVdata.Size = new System.Drawing.Size(488, 276);  
  139.             this.dGridCSVdata.TabIndex = 5;  
  140.             //   
  141.             // btnImport  
  142.             //   
  143.             this.btnImport.Cursor = System.Windows.Forms.Cursors.Hand;  
  144.             this.btnImport.FlatStyle = System.Windows.Forms.FlatStyle.System;  
  145.             this.btnImport.Location = new System.Drawing.Point(112, 92);  
  146.             this.btnImport.Name = "btnImport";  
  147.             this.btnImport.Size = new System.Drawing.Size(280, 26);  
  148.             this.btnImport.TabIndex = 4;  
  149.             this.btnImport.Text = "Import CSV Data";  
  150.             this.btnImport.Click += new System.EventHandler(this.btnImport_Click);  
  151.             //   
  152.             // btnOpenFileDlg  
  153.             //   
  154.             this.btnOpenFileDlg.Cursor = System.Windows.Forms.Cursors.Hand;  
  155.             this.btnOpenFileDlg.FlatStyle = System.Windows.Forms.FlatStyle.System;  
  156.             this.btnOpenFileDlg.Location = new System.Drawing.Point(368, 47);  
  157.             this.btnOpenFileDlg.Name = "btnOpenFileDlg";  
  158.             this.btnOpenFileDlg.Size = new System.Drawing.Size(24, 23);  
  159.             this.btnOpenFileDlg.TabIndex = 3;  
  160.             this.btnOpenFileDlg.Click += new System.EventHandler(this.btnOpenFileDlg_Click);  
  161.             //   
  162.             // txtCSVFilePath  
  163.             //   
  164.             this.txtCSVFilePath.BackColor = System.Drawing.SystemColors.Info;  
  165.             this.txtCSVFilePath.Location = new System.Drawing.Point(112, 48);  
  166.             this.txtCSVFilePath.Name = "txtCSVFilePath";  
  167.             this.txtCSVFilePath.ReadOnly = true;  
  168.             this.txtCSVFilePath.Size = new System.Drawing.Size(240, 20);  
  169.             this.txtCSVFilePath.TabIndex = 2;  
  170.             this.txtCSVFilePath.Text = "D:\\Test\\Test.csv";  
  171.             //   
  172.             // btnOpenFldrBwsr  
  173.             //   
  174.             this.btnOpenFldrBwsr.Cursor = System.Windows.Forms.Cursors.Hand;  
  175.             this.btnOpenFldrBwsr.FlatStyle = System.Windows.Forms.FlatStyle.System;  
  176.             this.btnOpenFldrBwsr.Location = new System.Drawing.Point(368, 24);  
  177.             this.btnOpenFldrBwsr.Name = "btnOpenFldrBwsr";  
  178.             this.btnOpenFldrBwsr.Size = new System.Drawing.Size(24, 23);  
  179.             this.btnOpenFldrBwsr.TabIndex = 1;  
  180.             this.btnOpenFldrBwsr.Click += new System.EventHandler(this.btnOpenFldrBwsr_Click);  
  181.             //   
  182.             // txtCSVFolderPath  
  183.             //   
  184.             this.txtCSVFolderPath.BackColor = System.Drawing.SystemColors.Info;  
  185.             this.txtCSVFolderPath.Location = new System.Drawing.Point(112, 24);  
  186.             this.txtCSVFolderPath.Name = "txtCSVFolderPath";  
  187.             this.txtCSVFolderPath.ReadOnly = true;  
  188.             this.txtCSVFolderPath.Size = new System.Drawing.Size(240, 20);  
  189.             this.txtCSVFolderPath.TabIndex = 1;  
  190.             this.txtCSVFolderPath.Text = "D:\\Test";  
  191.             //   
  192.             // openFileDialogCSVFilePath  
  193.             //   
  194.             this.openFileDialogCSVFilePath.Filter = "CSV Files (*.csv)|*.csv|DAT Files (*.dat)|*.dat";  
  195.             this.openFileDialogCSVFilePath.Title = "Select the CSV file for importing";  
  196.             this.openFileDialogCSVFilePath.FileOk += new System.ComponentModel.CancelEventHandler(this.openFileDialogCSVFilePath_FileOk);  
  197.             //   
  198.             // gbMainUploadData  
  199.             //   
  200.             this.gbMainUploadData.BackColor = System.Drawing.SystemColors.InactiveCaptionText;  
  201.             this.gbMainUploadData.Controls.Add(this.btnUpload);  
  202.             this.gbMainUploadData.FlatStyle = System.Windows.Forms.FlatStyle.System;  
  203.             this.gbMainUploadData.Location = new System.Drawing.Point(16, 432);  
  204.             this.gbMainUploadData.Name = "gbMainUploadData";  
  205.             this.gbMainUploadData.Size = new System.Drawing.Size(504, 56);  
  206.             this.gbMainUploadData.TabIndex = 1;  
  207.             this.gbMainUploadData.TabStop = false;  
  208.             this.gbMainUploadData.Text = "Save Data in Table";  
  209.             //   
  210.             // btnUpload  
  211.             //   
  212.             this.btnUpload.Cursor = System.Windows.Forms.Cursors.Hand;  
  213.             this.btnUpload.Enabled = false;  
  214.             this.btnUpload.FlatStyle = System.Windows.Forms.FlatStyle.System;  
  215.             this.btnUpload.Location = new System.Drawing.Point(112, 24);  
  216.             this.btnUpload.Name = "btnUpload";  
  217.             this.btnUpload.Size = new System.Drawing.Size(280, 23);  
  218.             this.btnUpload.TabIndex = 1;  
  219.             this.btnUpload.Text = "Save";  
  220.             this.btnUpload.Click += new System.EventHandler(this.btnUpload_Click);  
  221.             //   
  222.             // frmMain  
  223.             //   
  224.             this.AcceptButton = this.btnImport;  
  225.             this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);  
  226.             this.BackColor = System.Drawing.SystemColors.ActiveCaptionText;  
  227.             this.ClientSize = new System.Drawing.Size(536, 494);  
  228.             this.Controls.Add(this.gbMainUploadData);  
  229.             this.Controls.Add(this.gbMain);  
  230.             this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.Fixed3D;  
  231.             this.MaximizeBox = false;  
  232.             this.Name = "frmMain";  
  233.             this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;  
  234.             this.Text = "CSV Reader";  
  235.             this.Closing += new System.ComponentModel.CancelEventHandler(this.frmMain_Closing);  
  236.             this.Load += new System.EventHandler(this.frmMain_Load);  
  237.             this.gbMain.ResumeLayout(false);  
  238.             this.gbMain.PerformLayout();  
  239.             ((System.ComponentModel.ISupportInitialize)(this.dGridCSVdata)).EndInit();  
  240.             this.gbMainUploadData.ResumeLayout(false);  
  241.             this.ResumeLayout(false);  
  242.         }#endregion  
  243.         #region Main() Method  
  244.         /// <summary>  
  245.         /// The main entry point for the application.  
  246.         /// </summary>  
  247.         [STAThread]  
  248.         static void Main() {  
  249.             Application.EnableVisualStyles();  
  250.             Application.DoEvents();  
  251.             Application.Run(new frmMain());  
  252.         }#endregion  
  253.         #region Form Load  
  254.         private void frmMain_Load(object sender, System.EventArgs e) {  
  255.             try {  
  256.             } catch (Exception ex) {  
  257.                 MessageBox.Show(ex.Message);  
  258.             } finally {}  
  259.         }#endregion  
  260.         #region Open Folder Browser Button  
  261.         // On click of this button, the FOLDERBROWSERDIALOG opens where user can select the path of the folder   
  262.         // containing .csv files  
  263.         private void btnOpenFldrBwsr_Click(object sender, System.EventArgs e) {  
  264.             try {  
  265.                 if (fbdCSVFolder.ShowDialog() == DialogResult.OK) {  
  266.                     txtCSVFolderPath.Text = fbdCSVFolder.SelectedPath.Trim();  
  267.                 }  
  268.             } catch (Exception ex) {  
  269.                 MessageBox.Show(ex.Message);  
  270.             } finally {  
  271.             }  
  272.         }#endregion  
  273.         #region Open File Dialog Button  
  274.         // On click of this button, the openfiledialog opens where user can select .csv file   
  275.         private void btnOpenFileDlg_Click(object sender, System.EventArgs e) {  
  276.             try {  
  277.                 openFileDialogCSVFilePath.InitialDirectory = txtCSVFolderPath.Text.Trim();  
  278.                 if (openFileDialogCSVFilePath.ShowDialog() == DialogResult.OK) {  
  279.                     txtCSVFilePath.Text = openFileDialogCSVFilePath.FileName.Trim();  
  280.                 }  
  281.             } catch (Exception ex) {  
  282.                 MessageBox.Show(ex.Message);  
  283.             } finally {}  
  284.         }#endregion  
  285.         #region Function For Importing Data From CSV File  
  286.         public DataSet ConnectCSV() {  
  287.             DataSet ds = new DataSet();  
  288.             string fileName = openFileDialogCSVFilePath.FileName;  
  289.             CsvReader reader = new CsvReader(fileName);  
  290.             ds = reader.RowEnumerator;  
  291.             dGridCSVdata.DataSource = ds;  
  292.             dGridCSVdata.DataMember = "TheData";  
  293.             return ds;  
  294.         }  
  295.         #endregion  
  296.         #region Button Import CSV Data  
  297.         private void btnImport_Click(object sender, System.EventArgs e) {  
  298.             try {  
  299.                 if (txtCSVFolderPath.Text == "") {  
  300.                     MessageBox.Show("The Folder Path TextBox cannot be empty.", "Warning");  
  301.                     return;  
  302.                 } else if (txtCSVFilePath.Text == "") {  
  303.                     MessageBox.Show("The File Path TextBox cannot be empty.", "Warning");  
  304.                     return;  
  305.                 } else {  
  306.                     //int intLengthOfFileName = txtCSVFilePath.Text.Trim().Length;  
  307.                     //int intLastIndex = txtCSVFilePath.Text.Trim().LastIndexOf("\\");  
  308.                     //strCSVFile = txtCSVFilePath.Text.Trim().Substring(intLastIndex, intLengthOfFileName - intLastIndex);  
  309.                     //strCSVFile = strCSVFile.Remove(0, 1).Trim();  
  310.                     // writeSchema();  
  311.                     ConnectCSV();  
  312.                     btnUpload.Enabled = true;  
  313.                 }  
  314.             } catch (Exception ex) {  
  315.                 MessageBox.Show(ex.Message);  
  316.             } finally {}  
  317.         }#endregion  
  318.         #region Button Insert Data  
  319.         // Here we will insert the imported data in our database  
  320.         private void btnUpload_Click(object sender, System.EventArgs e) {  
  321.             try {  
  322.                 // Create an SQL Connection  
  323.                 //SqlConnection con1 = new SqlConnection(ReadConFile().Trim());  
  324.                 OleDbConnection con1 = new OleDbConnection();  
  325.                 con1.ConnectionString = @  
  326.                 "Provider=Microsoft.ACE.OLEDB.12.0;Data Source = C:\\Users\\KML Surani\\Documents\\ImportCSV.accdb;Persist Security Info=False;";  
  327.                 OleDbCommand cmd = new OleDbCommand();  
  328.                 // Create Dataset   
  329.                 DataSet da = new DataSet();  
  330.                 // To actually fill the dataset, Call the function ImportCSV and assign the returned   
  331.                 // dataset to new dataset as below  
  332.                 da = this.ConnectCSV();  
  333.                 // Now we will collect data from data table and insert it into database one by one  
  334.                 // Initially there will be no data in database so we will insert data in first two columns  
  335.                 // and after that we will update data in same row for remaining columns  
  336.                 // The logic is simple. 'i' represents rows while 'j' represents columns  
  337.                 con1.Open();  
  338.                 cmd.Connection = con1;  
  339.                 cmd.CommandType = CommandType.Text;  
  340.                 for (int i = 0; i <= da.Tables["TheData"].Rows.Count - 1; i++) {  
  341.                     cmd.CommandText = "Insert into tblImportCSV (Name,City) values('" + da.Tables["TheData"].Rows[i]["Name"] + "','" + da.Tables["TheData"].Rows[i]["City"] + "')";  
  342.                     // For UPDATE statement, in where clause you need some unique row   
  343.                     //identifier. We are using ‘srno’ in WHERE clause.   
  344.                     //cmd1.CommandText = "Update Test set " + da.Tables["Stocks"].Columns[j].ColumnName.Trim() + " = '" + da.Tables["Stocks"].Rows[i].ItemArray.GetValue(j) + "' where srno =" + (i + 1);  
  345.                     cmd.ExecuteNonQuery();  
  346.                     //cmd1.ExecuteNonQuery();  
  347.                 }  
  348.                 con1.Close();  
  349.             } catch (Exception ex) {  
  350.                 MessageBox.Show(ex.Message);  
  351.             } finally {  
  352.                 btnUpload.Enabled = false;  
  353.             }  
  354.         }#endregion  
  355.         #region Form Closing  
  356.         private void frmMain_Closing(object sender, System.ComponentModel.CancelEventArgs e) {  
  357.             try {  
  358.                 Application.Exit();  
  359.             } catch (Exception ex) {  
  360.                 MessageBox.Show(ex.Message);  
  361.             } finally {}  
  362.         }#endregion  
  363.         private void openFileDialogCSVFilePath_FileOk(object sender, CancelEventArgs e) {  
  364.         }  
  365.     }  
  366. }  
In the same way, you can also upload .xlsx file in desktop application. 
Next Recommended Reading How to Create CSV File using C#?