How to Convert DataTable to CSV in C#

This article will walk you through converting a DataTable to a CSV file using C#. To begin, we must know what CSV is, so let’s get into it.

The data in a Comma Split Values, also known as a CSV file, are separated into their respective columns by commas rather than spaces. Another usage of a CSV file is to open the file in Excel immediately when the data are automatically put into the appropriate cells in Excel.

Convert DataTable to CSV in C#

The first step in converting a DataTable to a CSV file is to create a DataTable. The steps involved in doing so are outlined in the following paragraphs.

Create and Fill the DataTable

• To begin, we must import the following libraries:

  using System;
  using System.Collections.Generic;
  using System.Data;
  using System.IO;
  using System.Linq;
  using System.Text;
  using System.Threading.Tasks;
  

• We created a class named datacreation with a method called CreateData() that generates a DataTable as its return value.

```c#
public static class datacreation {
  public static DataTable CreateData() {}
}
```

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test:
  command: c#
  expected_output: |
    Compilation failed: 1 error(s), 0 warnings
-->

• To begin with data entry, we’ve to create a DataTable object named dt in CreateData().

  DataTable dt = new DataTable();
  

• After the object has been initialized, the next step is to add data columns to the DataTable dt. We have included the Rollnum, Firstname, Lastname, and Subject fields, and you are free to add any other areas you need.

```c#
dt.Columns.Add("RollNum", typeof(int));
dt.Columns.Add("Firstname", typeof(string));
dt.Columns.Add("Lastname", typeof(string));
dt.Columns.Add("Subjects", typeof(string));
```

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test:
  command: c#
  expected_output: |
    Compilation failed: 1 error(s), 0 warnings
-->

• Next, fill in the information in these columns or fields.

  dt.Rows.Add(3227, "Zeeshan", "Khan", "C#");
  dt.Rows.Add(3290, "Bubby", "Zeeshan", "Java");
  dt.Rows.Add(3247, "Osama", "shanii", "C++");
  dt.Rows.Add(3156, "Haseeb", "Bhatti", "Python");
  dt.Rows.Add(3223, "Saad", "Shukhri", "Mongo Db");
  dt.Rows.Add(3267, "Sheraz", "Malik", "MySQl");
  dt.Rows.Add(3288, "Nabeel", "Sindho", "PHP");
  dt.Rows.Add(3299, "Ahsan", "Chishti", "C");
  

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test:
  command: c#
  expected_output: |
    Compilation failed: 1 error(s), 0 warnings
-->

• The CreateData() function will return a table of the DataTable type.

  return dt;
  

Convert the DataTable to CSV in C#

After we have created the DataTable, the next step is to write the code that will convert the DataTable to CSV.

• We’ve added a new method called ConvertTocsv to the implementCSV class. The variables dt and path are the parameters it takes.

  public static class implementCSV {
    public static void ConvertTocsv(this DataTable dt, string path) {}
  }
  

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test:
  command: c#
  expected_output: |
    Compilation failed: 1 error(s), 0 warnings
-->

• In the ConvertTocsv method, we’ve created a StreamWriter object called s, which will write data in the specified path.

  StreamWriter s = new StreamWriter(path, false);
  

• We will use a for loop to split the data from the DataTable by inserting commas between each column.

  for (int i = 0; i < dt.Columns.Count; i++) {
    s.Write(dt.Columns[i]);
    if (i < dt.Columns.Count - 1) {
      s.Write(",");
    }
  }
  s.Write(s.NewLine);
  

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test:
  command: c#
  expected_output: |
    Compilation failed: 1 error(s), 0 warnings
-->

• Following that, we will now utilize a foreach loop, which will write data from the DataTable dt with a comma.

  foreach (DataRow dr in dt.Rows) {
    for (int i = 0; i < dt.Columns.Count; i++) {
      if (!Convert.IsDBNull(dr[i])) {
        string value = dr[i].ToString();
        if (value.Contains(',')) {
          value = String.Format("\"{0}\"", value);
          s.Write(value);
        } else {
          s.Write(dr[i].ToString());
        }
      }
      if (i < dt.Columns.Count - 1) {
        s.Write(",");
      }
    }
    s.Write(s.NewLine);
  }
  

<!--
test:
  command: c#
  expected_output: |
    Compilation failed: 1 error(s), 0 warnings
-->

Complete Source Code

using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DataTableExport {
  public static class datacreation {
    public static DataTable CreateData() {
      DataTable dt = new DataTable();
      dt.Columns.Add("RollNum", typeof(int));
      dt.Columns.Add("Firstname", typeof(string));
      dt.Columns.Add("Lastname", typeof(string));
      dt.Columns.Add("Subjects", typeof(string));

      dt.Rows.Add(3227, "Zeeshan", "Khan", "C#");
      dt.Rows.Add(3290, "Bubby", "Zeeshan", "Java");
      dt.Rows.Add(3247, "Osama", "shanii", "C++");
      dt.Rows.Add(3156, "Haseeb", "Bhatti", "Python");
      dt.Rows.Add(3223, "Saad", "Shukhri", "Mongo Db");
      dt.Rows.Add(3267, "Sheraz", "Malik", "MySQl");
      dt.Rows.Add(3288, "Nabeel", "Sindho", "PHP");
      dt.Rows.Add(3299, "Ahsan", "Chishti", "C");
      return dt;
    }
  }
  public static class implementCSV {
    public static void ConvertTocsv(this DataTable dt, string path) {
      StreamWriter s = new StreamWriter(path, false);
      for (int i = 0; i < dt.Columns.Count; i++) {
        s.Write(dt.Columns[i]);
        if (i < dt.Columns.Count - 1) {
          s.Write(",");
        }
      }
      s.Write(s.NewLine);
      foreach (DataRow dr in dt.Rows) {
        for (int i = 0; i < dt.Columns.Count; i++) {
          if (!Convert.IsDBNull(dr[i])) {
            string value = dr[i].ToString();
            if (value.Contains(',')) {
              value = String.Format("\"{0}\"", value);
              s.Write(value);
            } else {
              s.Write(dr[i].ToString());
            }
          }
          if (i < dt.Columns.Count - 1) {
            s.Write(",");
          }
        }
        s.Write(s.NewLine);
      }
      s.Close();
    }
  }
}

Create a Windows Form

After creating the data in the DataTable and separating it using commas, the next step is constructing a Windows Form where the data can be shown and then converted to the .csv format.

• To get started, let’s create a Windows Form, as shown below, and inside it, we’ll put a DataGridView and a button called Convert data to CSV. A DataGridView that displays the created data and a button that converts the DataTable into CSV are included.

  

• When you have finished executing the Windows Form, it will look like this:

  

Write the Code for the Windows Form

After we have created the Windows Form, the next step is to write the code for the Convert data to CSV button.

• Initialize an object and populate it with data by calling the methods listed below.

  DataTable dt = datacreation.CreateData();
  

• OpenSavefileDialog() can be used to save the file with the given name.

  string filename = OpenSavefileDialog();
  

• ConvertTocsv will be used to create a CSV file from the data we’ve created.

  dt.ConvertTocsv(filename);
  

Windows Form Source Code

public Form1() {
  InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e) {
  DataTable dt = datacreation.CreateData();
  dataGridView1.DataSource = dt;
}

private void btnCSV_Click(object sender, EventArgs e) {
  DataTable dt = datacreation.CreateData();
  string filename = OpenSavefileDialog();
  dt.ConvertTocsv(filename);
}

private string OpenSavefileDialog() {
  string filename = null;
  SaveFileDialog saveFileDialog = new SaveFileDialog();
  saveFileDialog.Filter = "csv File|*.csv";
  saveFileDialog.Title = "Save";
  DialogResult dialogResult = saveFileDialog.ShowDialog();
  if (dialogResult == DialogResult.OK) {
    filename = saveFileDialog.FileName;
  }
  return filename;
}