来自MySQL的数据显示为＆＃39; 0＆＃39;在实时图表中

Question

我正在使用MySQL的数据创建一个实时图表，但我找不到办法。

        float  Sen3, Sen2, Sen5;
        string Sen3Value, Sen2Value, Sen5Value;

        //open connection to database
        private void ShowData(object sender, EventArgs e)
    {
        MySqlConnection connection = new MySqlConnection(myConnectionString);
        connection.Open();
        try
        {
            MySqlCommand cmd = connection.CreateCommand();
            cmd.CommandText = "Select * FROM sensor";
            MySqlDataAdapter adap = new MySqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            adap.Fill(ds);
            dataGridView1.DataSource = ds.Tables[0].DefaultView;
            ///////////////////////////////////////////////////////
            this.dataGridView1.Sort(this.dataGridView1.Columns["id"], ListSortDirection.Descending);
            //////////////////////////////////////////////////////

            int nRowIndex = dataGridView1.Rows.Count;
            int first = dataGridView1.Rows.Count - nRowIndex;
            dataGridView1.Rows[first].Selected = true;
            if (dataGridView1.Rows[first].Cells[2].Value != null)
            {
                Sen3Value = dataGridView1.Rows[first].Cells[3].Value.ToString();
                Sen3 = float.Parse(Sen3Value);
            }

            if (dataGridView1.Rows[first].Cells[2].Value != null)
            {

                Sen2Value = dataGridView1.Rows[first].Cells[4].Value.ToString();
                Sen2 = float.Parse(Sen2Value);
            }

            if (dataGridView1.Rows[first].Cells[2].Value != null)
            {

                Sen5Value = dataGridView1.Rows[first].Cells[5].Value.ToString();
                Sen5 = float.Parse(Sen5Value);
            }
        }
        catch (Exception)
        {
            throw;
        }
        finally
        {
            if (connection.State == ConnectionState.Open)
            {
                connection.Clone();
            }
        }
    }
        // Create a new chart.
        ChartControl ManhattanBarChart = new ChartControl();

        // Add a bar series to it.
        DevExpress.XtraCharts.Series series1 = new DevExpress.XtraCharts.Series("Series 1", ViewType.ManhattanBar);
        DevExpress.XtraCharts.Series series2 = new DevExpress.XtraCharts.Series("Series 2", ViewType.ManhattanBar);

        // Add points to the series.
        series1.Points.Clear();
        series2.Points.Clear();
        series1.Points.Add(new SeriesPoint("A", Sen2));
        series1.Points.Add(new SeriesPoint("B", 8));
        series1.Points.Add(new SeriesPoint("C", 9));
        series1.Points.Add(new SeriesPoint("D", 10));
        series2.Points.Add(new SeriesPoint("A", 3));
        series2.Points.Add(new SeriesPoint("B", 4));
        series2.Points.Add(new SeriesPoint("C", 5));
        series2.Points.Add(new SeriesPoint("D", Sen2));

如代码所示，Sen2是来自MySQL的数据，但在运行代码时它显示为0。任何帮助将不胜感激！

编辑：添加＆＃34;打开与数据库的连接＆＃34;码

请原谅我缺少C＃编程，因为这是我的第一个需要此项目的项目