string commandString = "select sum, date from wallettbl order by date";
cmd = new SqlCommand(commandString, con);
con.Open();
SqlDataReader dataReader;
dataReader = cmd.ExecuteReader();

        while (dataReader.Read())
        {
         this.chart1.Series["Series1"].Points.AddXY(dataReader["sum"], dataReader["date"]);
         this.chart1.ChartAreas["ChartArea1"].AxisX.LabelStyle.Format = "dd/mm/yyyy";
       }

        con.Close();