Load DataTable from IDataReader

Probably the coolest feature is that the DataTable can now be loaded via a IDataReader ( SqlDataReader for example ) without the need for a DataAdapter ( SqlDataAdapter ).

The DataTable now has a Load method that accepts an IDataReader as an argument:

 DataTable.Load(IDataReader datareader)

Here is an example of loading the DataTable with an IDataReader:

private void Form1_Load(object sender,
                           EventArgs e)
                           {
                           dataGridView1.DataSource = GetData();
                           }
                           
                           private DataTable GetData()
                           {
                           DataTable dt = new DataTable();
                           
                           using (SqlConnection connection
                           = new SqlConnection("ConnectionString"))
                           using (SqlCommand command = new SqlCommand())
                           {
                           command.Connection = connection;
                           command.CommandText = "SELECT * FROM Customers";
                           
                           connection.Open();
                           using (SqlDataReader reader =
                                       command.ExecuteReader
                           (CommandBehavior.CloseConnection))
                           {
                           dt.Load(reader);
                           }
                           }
                           
                           return dt;
                           }

DataTable.CreateDataReader Method

If that wasn't enough, the DataTable also has a CreateDataReader method that returns a DataTableReader:

public DataTableReader CreateDataReader ()

This means you can use a DataTable as the source for anything that wants a DataTableReader, DbDataReader or IDataReader.  Since the DataTable can be cached and the DataReader cannot, this opens up some extra flexibility in your data access layer when you decide you need caching at some point.

Below is a bit of a far fetched, but descriptive example of the CreatDataReader Method of the DataTable.  I am manually creating a DataTable, adding myself as a Customer DataRow, and then calling CreateDataReader to return an IDataReader object.  This is then used as input in the DataTable.Load Method of another DataTable (dt), which is then used as a DataSource to the DataGridView.

private void Form1_Load(object sender, EventArgs e)
{
    DataTable dt = new DataTable();
    dt.Load(GetReader());
    dataGridView1.DataSource = dt;

}

private IDataReader GetReader()
{
    DataTable dt = new DataTable();
    dt.Columns.Add("ID", typeof(string));
    dt.Columns.Add("Firstname", typeof(string));
    dt.Columns.Add("Lastname", typeof(string));

    dt.Rows.Add((new Object[] {"HAYD", "David", "Hayden"}));

    return dt.CreateDataReader();
}

DataTable.ReadXml and WriteXml

Like the DataSet, the DataTable now also supports ReadXml, ReadXmlSchema, WriteXml, and WriteXmlSchema.  This is phenomenal when used with CreateDataReader, etc.

private void Form1_Load(object sender, EventArgs e)
{
    dataGridView1.DataSource = GetDataTable();
}

private DataTable GetDataTable()
{           
    DataTable dt = new DataTable();

    dt.ReadXmlSchema("CustomerSchema.xml");
    dt.ReadXml("CustomerData.xml");
    return dt;
}

Conclusion

The DataTable in ADO.NET 2.0 opens up a whole new world of possibilities when dealing with a single resultset that doesn't need all the baggage that comes with the DataSet.