DataSet1 ds = new DataSet1(); MessageBox.Show("Coulumns.Count: " + ds.Table2.Columns.Count.ToString(), "before"); SqlDataAdapter adapter = new SqlDataAdapter(); adapter.SelectCommand = new SqlCommand("SELECT field1, field2, field3 FROM Table2", new SqlConnection("Data Source=localhost;Initial Catalog=Test;Integrated Security=SSPI;")); adapter.Fill(ds, ds.Table2.TableName); MessageBox.Show("Coulumns.Count: " + ds.Table2.Columns.Count.ToString(), "after");The first msgbox (with title before) displays a column count of 2 which is what I expect, but the 2nd msgbox (with title after) displays a column count of 3 which is not really what I expect.