private void btn_Click(object sender, EventArgs e)
        { 

            DBHelper db = new DBHelper();
            DataSet ds = db.GetDataList();
            this.dataGridView1.DataSource = ds.Tables[0];

            DataSet ds1 = db.GetResportLine();
            DataSet ds2 = db.GetResportLine2();
            DataSet ds3 = db.GetResportLine3();

            DataTable dt1 = ds1.Tables[0];
            DataTable dt2 = ds2.Tables[0];
            DataTable dt3 = ds3.Tables[0];
             
            //chart1.ChartAreas[0].AxisX.Maximum = 1000;//设定x轴的最大值
            //chart1.ChartAreas[0].AxisY.Maximum = 100;//设定y轴的最大值

            //chart1.ChartAreas[0].AxisX.Minimum = 1;//设定x轴的最小值
            //chart1.ChartAreas[0].AxisY.Minimum = 0;//设定y轴的最小值

            //第一条数据
            Series ss = new Series("dt1");   //这里 dt1 ,dt2 任意取名称，但要唯一
            ss.Points.DataBind(dt1.AsEnumerable(), "xzhou", "yzhou", "");
            ss.XValueType = ChartValueType.DateTime; //设置X轴
            ss.ChartType = SeriesChartType.Spline;   //设置Y轴为折线
            chart1.Series.Add(ss);

            //第二条数据
            Series ss2 = new Series("dt2");
            ss2.Points.DataBind(dt2.AsEnumerable(), "xzhou2", "yzhou2", "");
            ss2.XValueType = ChartValueType.DateTime; //设置X轴
            ss2.ChartType = SeriesChartType.Spline;   //设置Y轴为折线
            chart1.Series.Add(ss2);

            //第三条数据
            Series ss3 = new Series("dt3");
            ss3.Points.DataBind(dt3.AsEnumerable(), "xzhou2", "yzhou2", "");
            ss3.XValueType = ChartValueType.DateTime; //设置X轴
            ss3.ChartType = SeriesChartType.Spline;   //设置Y轴为折线
            chart1.Series.Add(ss3);
             
        }