Exporting data to a CSV, tab delimited or other text format

3.4 (5 votes)

A question that often comes up in forums is how to export data to a CSV file, or other text format. Here's a method that takes data from a DataReader and writes it to a file.

[C#]

using System;
using System.Data;
using System.Data.OleDb;
using System.IO;
using System.Text;
using System.Web;

public static void WriteToTextFile(string separator, string filename)
{
  string ConnStr = "Provider=Microsoft.Jet.OleDb.4.0;" +
				"Data Source=|DataDirectory|Northwind.mdb;";
  string query = "SELECT * FROM Customers";
  string sep = separator;

  StreamWriter sw = new StreamWriter(HttpContext.Current.Server.MapPath(filename));
  using (OleDbConnection Conn = new OleDbConnection(ConnStr))
  {
    using (OleDbCommand Cmd = new OleDbCommand(query, Conn))
    {
      Conn.Open();
      using (OleDbDataReader dr = Cmd.ExecuteReader())
      {
        int fields = dr.FieldCount - 1;
        while (dr.Read())
        {
          StringBuilder sb = new StringBuilder();
          for (int i = 0; i <= fields; i++)
          {
            if (i != fields)
            {
              sep = sep;
            }
            else
            {
              sep = "";
            }
            sb.Append(dr[i].ToString() + sep);

          }
          sw.WriteLine(sb.ToString());
        }
      }
    }
  }
}
[VB]

Imports System
Imports System.Data
Imports System.Data.OleDb
Imports System.IO
Imports System.Text
Imports System.Web

Public Shared Sub WriteToTextFile(ByVal separator As String, ByVal filename As String)
  Dim ConnStr As String = "Provider=Microsoft.Jet.OleDb.4.0;" + 
          "Data Source=|DataDirectory|Northwind.mdb;"
  Dim query As String = "SELECT * FROM Customers"
  Dim sep As String = separator

  Dim sw As New StreamWriter(HttpContext.Current.Server.MapPath(filename))
  Using Conn As New OleDbConnection(ConnStr)
    Using Cmd As New OleDbCommand(query, Conn)
    Conn.Open()
      Using dr As OleDbDataReader = Cmd.ExecuteReader()
        Dim fields As Integer = dr.FieldCount - 1
        While dr.Read()
          Dim sb As New StringBuilder()
          Dim i As Integer = 0
          While i <= fields
            If i <> fields Then
              sep = sep
            Else
              sep = ""
            End If
            sb.Append(dr(i).ToString() + sep)
            i += 1
          End While
          sw.WriteLine(sb.ToString())
        End While
      End Using
    End Using
  End Using
End Sub

And in both cases, the method is called by simply passing the separator and filename in as strings:

WriteToTextFile(",", "vfile.txt")

Date Posted:
Last Updated:
Posted by:
Total Views to date: 50372

4 Comments

- Larry Grimes

Why would you EVER write, "sep = sep;"?

C#: if (i == fields) sep = "";VB: If (i = fields) Then sep = ""

NOTE: I ALWAYS use parens to denote identities, it REALLY helps clarify code, even in "If" statements and even if it doesn't seem necessary. It sure helps someone else reading your code!

Maybe, the ONLY time I could see it used is in tertiary commands:

sep = ((i == fields) ? "" : sep);

- Mike

@Larry

Thanks for your comments. You are quite right, of course. At some stage, I might find the time to go over all these older posts and improve the code. A lot of them could do with improvement!

- newbie

Can I just use WriteToTextFile("|", "vfile.txt") when tab delimeted?

- Mike

@newbie

Your separator appears to be a pipe rather than a tab. Tabs are usually \t in C# or vbTab in VB.

Recent Comments

satyabrata 19/06/2016 18:53
In response to Entity Framework Code First and Stored Procedures
Nice article. Thanks. The menu on this website not working in mobile....

satyabrata 16/05/2016 06:28
In response to Implementing SQL Server Full-Text Search In An ASP.NET MVC Web Application With Entity Framework
This is great. Thanks for sharing....

sharey 06/05/2016 13:15
In response to The Best Way To Import Data From Excel To SQL Server via ASP.NET
nice work gentleman.Really helpfull....

Satyabrata Mohapatra 20/04/2016 04:36
In response to The Best Way To Import Data From Excel To SQL Server via ASP.NET
Another beauty !!!! Thanks for sharing....

Avinash Setty 18/04/2016 18:39
In response to Exploring Prefix: A Free ASP.NET Profiling Tool
This tool is awesome! I am very thankful for introducing this tool for us! By any chance, do you is...

flyingtigerfan 17/04/2016 22:56
In response to Request.Form Is Empty When Posting To ASPX Page
Thanks - spent hours trying to figure this out. I'm out of date and trying to start working on some...

Darren Evans 12/04/2016 16:42
In response to Exploring Prefix: A Free ASP.NET Profiling Tool
'Tis indeed a marvellous thing. Just waiting on its appearance for ASP.NET Core. Hopefully not long...

Arkady 03/04/2016 12:09
In response to Request.Form Is Empty When Posting To ASPX Page
Thank you! I spent a day to understand what problem is before I found your article! But I made of...

satyabrata 03/04/2016 03:50
In response to Exploring Prefix: A Free ASP.NET Profiling Tool
This is great!!!!!...

John Dave Bumatay 01/04/2016 02:01
In response to Windows Authentication With ASP.NET Web Pages
+1 ! This worked for me like a magic!~ thank you very much Mike! ;)...