How to Export DataTable to CSV in C#

How to Export DataTable to CSV in C#?

Create a Windows Forms Application in Visual Studio. then design a simple UI allows you to export data from DataTable to CSV file as shown below.

Creating a WriteDataTable method allows you to write data from DataTable to text or csv file in c#.

public void WriteDataTable(DataTable dataTable, TextWriter writer, bool header)
{
    if (header)
    {
        // Create the CSV file and write the headers
        IEnumerable<string> headerValues = dataTable.Columns
            .OfType<DataColumn>()
            .Select(column => QuoteValue(column.ColumnName));
        writer.WriteLine(string.Join(",", headerValues));
    }
    IEnumerable<string> items = null;
    foreach (DataRow row in dataTable.Rows)
    {
        items = row.ItemArray.Select(o => QuoteValue(o?.ToString() ?? string.Empty));
        writer.WriteLine(string.Join(",", items));
    }
    writer.Flush();
}

private string QuoteValue(string value)
{
    return string.Concat("\"", value.Replace("\"", "\"\""), "\"");
}

Data in the csv file is separated by commas. If you want to export header data you need to write column headers first, then data.

Next, Add a bindingsource to the DataGridView allows you to retrieve customer table from the Northwind database.

private void frmExportDataTableToCsv_Load(object sender, EventArgs e)
{
    // TODO: This line of code loads data into the 'appData.Customers' table. You can move, or remove it, as needed.
    this.customersTableAdapter.Fill(this.appData.Customers);
}

Double-click on the Export button to generate an event handler for its click event allows you to export datatable to csv file.

// c# export datatable to csv
private void btnExportData_Click(object sender, EventArgs e)
{
    using (SaveFileDialog sfd = new SaveFileDialog() { Filter = "CSV files|*.csv" })
    {
        if (sfd.ShowDialog() == DialogResult.OK)
        {
            try
            {
                using (StreamWriter writer = new StreamWriter(sfd.FileName))
                {
                    WriteDataTable(this.appData.Customers.CopyToDataTable(), writer, true);
                }
                MessageBox.Show("You have successfully exported the file.", "Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Message", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
    }
}

Build and run your application. When you click the button, it will export the data from the DataTable to a CSV file. You can easily open csv file with Microsoft Excel.

C# DataSet to CSV

To export a DataSet to a CSV file in C#, you can loop through the tables and rows of the DataSet, and write the data to a CSV file.

using System;
using System.Data;
using System.IO;
using System.Text;

class Program
{
    static void Main()
    {
        // Sample DataSet for demonstration
        DataSet dataSet = new DataSet();
        DataTable table = new DataTable("SampleTable");
        table.Columns.Add("Id", typeof(int));
        table.Columns.Add("Name", typeof(string));
        table.Columns.Add("Age", typeof(int));
        table.Rows.Add(1, "John", 30);
        table.Rows.Add(2, "Jane", 25);
        table.Rows.Add(3, "Bob", 35);

        dataSet.Tables.Add(table);

        // Export DataSet to CSV
        ExportDataSetToCsv(dataSet, "output.csv");
    }

    static void ExportDataSetToCsv(DataSet dataSet, string filePath)
    {
        StringBuilder csvContent = new StringBuilder();

        // Loop through each table in the DataSet
        foreach (DataTable table in dataSet.Tables)
        {
            // Write the header row (column names)
            string columnNames = string.Join(",", table.Columns.Cast<DataColumn>().Select(col => col.ColumnName));
            csvContent.AppendLine(columnNames);

            // Loop through each row in the table
            foreach (DataRow row in table.Rows)
            {
                string rowValues = string.Join(",", row.ItemArray.Select(val => $"\"{val.ToString().Replace("\"", "\"\"")}\""));
                csvContent.AppendLine(rowValues);
            }
        }

        // Write the CSV content to the file
        File.WriteAllText(filePath, csvContent.ToString());
        Console.WriteLine("Data exported to " + filePath);
    }
}

In this example:

1. DataSet: A DataSet is created with one DataTable containing sample data (ID, Name, Age).
2. ExportDataSetToCsv: The function loops through each table in the DataSet and exports its contents to a CSV file.
   • It first writes the column names (header).
   • Then it loops through each row and writes the values as comma-separated strings, handling any quotes in the data by escaping them with double quotes ("").
3. File Writing: The content is written to the specified CSV file using File.WriteAllText.

You can modify the code to export a DataSet with multiple tables, or customize the file path as needed.