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);                     }