{
string connStr = ConfigurationManager.ConnectionStrings["cn"].ConnectionString;
SqlConnection mySQLconnection = new SqlConnection(connStr);
if (mySQLconnection.State == ConnectionState.Closed)
{
  mySQLconnection.Open();
}
SqlCommand mySqlCommand = new SqlCommand("select * from tablename ORDER BY [ID] DESC;", mySQLconnection);
SqlDataAdapter mySqlAdapter = new SqlDataAdapter(mySqlCommand);
DataSet myDataSet = new DataSet();
mySqlAdapter.Fill(myDataSet);
GridView1.DataSource = myDataSet;
GridView1.DataBind();
}