using (SqlConnection sqlCon=new SqlConnection (ConStr))
{
SqlDataAdapter sda = new SqlDataAdapter("SELECT * FROM tb2 t",sqlCon);
// DataSet ds = new DataSet();
DataTable dt = new DataTable();
//ds.EnforceConstraints = false;
dt.BeginLoadData();
sda.Fill(dt);
dt.EndLoadData();
DataTableReader DtReader= dt.CreateDataReader();
DataTable dt2 = new DataTable();
dt2.Load(DtReader);
MessageBox.Show(DtReader.HasRows.ToString ());
this.dataGridView1.DataSource = DtReader;
}