Export DataTable To CSV In C#

public static class OperationsUtility
{
    public static DataTable CreateDataTable()
    {
        DataTable table = new DataTable();

        // Define columns
        table.Columns.Add("ID", typeof(int));
        table.Columns.Add("NAME", typeof(string));
        table.Columns.Add("CITY", typeof(string));

        // Add data rows
        table.Rows.Add(111, "Devesh", "Ghaziabad");
        table.Rows.Add(222, "ROLI", "KANPUR");
        table.Rows.Add(102, "ROLI", "MAINPURI");
        table.Rows.Add(212, "DEVESH", "KANPUR");
        table.Rows.Add(102, "NIKHIL", "GZB");
        table.Rows.Add(212, "HIMANSHU", "NOIDa");
        table.Rows.Add(102, "AVINASH", "NOIDa");
        table.Rows.Add(212, "BHUPPI", "GZB");

        return table;
    }
}

• Create a static class as per the code below.

  public static class  CSVUtlity  { }

• Add an Extension method as in the following.

  public static void ToCSV(this DataTable dtDataTable, string strFilePath){ }            

• After adding the Extension method the ToCSV method is now appearing in the list below.
  
• The following is the code to convert the DataTable to CSV.

  public static void ToCSV(this DataTable dtDataTable, string strFilePath) {  
      StreamWriter sw = new StreamWriter(strFilePath, false);  
      //headers    
      for (int i = 0; i < dtDataTable.Columns.Count; i++) {  
          sw.Write(dtDataTable.Columns[i]);  
          if (i < dtDataTable.Columns.Count - 1) {  
              sw.Write(",");  
          }  
      }  
      sw.Write(sw.NewLine);  
      foreach(DataRow dr in dtDataTable.Rows) {  
          for (int i = 0; i < dtDataTable.Columns.Count; i++) {  
              if (!Convert.IsDBNull(dr[i])) {  
                  string value = dr[i].ToString();  
                  if (value.Contains(',')) {  
                      value = String.Format("\"{0}\"", value);  
                      sw.Write(value);  
                  } else {  
                      sw.Write(dr[i].ToString());  
                  }  
              }  
              if (i < dtDataTable.Columns.Count - 1) {  
                  sw.Write(",");  
              }  
          }  
          sw.Write(sw.NewLine);  
      }  
      sw.Close();  
  } 

Step 4. Export to CSV on button click

private void btnCSV_Click(object sender, EventArgs e) {  
    DataTable dt = OperationsUtlity.createDataTable();  
    string filename = OpenSavefileDialog();  
    dt.ToCSV(filename);  
} 

Step 5. Call ToCSV method

dt.ToCSV() will call the ToCSV method defined in the CSVutlity class.

Step 6. Build and run the project

Now build and run the project. Click on the button to export data. The output file will be test.csv.

When you open the CSV file in Notepad, you will see this

By default, this file opens in Excel. Double-click to open this file in Excel. This is how the file looks like.

Conclusion

We have learned how to use a C# extension method and learned how to export a DataTable to a CSV file.

References and more

Learn here about extension methods.

• Extension Methods in C#
• DataTable in C#
• Export a DataTable to Excel
• Export DataTable to PDF