数据

A:取出数据表里的数据

单个数据：

using System.Data.SqlClient;



using(SqlConnection con = new SqlConnection("Data Source=.;uid=sa;pwd=sa;Database=Northwind"))
{
con.Open();
string strsql6 = "select count(sno) from student where cno='" + class1 + "' and cet4>425";
SqlCommand cmd = new SqlCommand(strsql6,con);
this.TextBox1.Text = cmd.ExecuteScalar().ToString();
}

　　

多字段的话，要参考ExecuteReader或者用SqlAdapter的fill方法，装到DataTable里面，然后写for循环，table.Rows[i]["字段名"].ToString()可以读取字段的值

B:为取出数据根据桩号画点画线。泛型的使用

 #region 显示测线
        private void View_Btn_Click(object sender, EventArgs e)
        {


            // main.view();
            //先循环每一条线
            for (int i = 0; i < Describ_dataGridView.Rows.Count; i++)
            {
                string lineNa = Convert.ToString(Describ_dataGridView.Rows[i].Cells[1].Value);

                //画线
                this.newLine(lineNa);
                //画点
                this.newPoint(lineNa);

            }
            this.Hide();
        }
        #endregion


        #region 画点
        private void newPoint(string lineNa)
        {
            FormMain main = (FormMain)this.Owner;
            List<CPoint> list = getPoints(lineNa);
            for (int i = 0; i < list.Count; i++)
            {


                double XPoint = list[i].lng;//从表中取数据
                double YPoint = list[i].lat;

                IActiveView pActiveView = main.axMapControl1.ActiveView;
                IPoint pPoint = new ESRI.ArcGIS.Geometry.Point();
                pPoint.PutCoords(XPoint, YPoint);
                IMarkerElement pMarkerElement;
                pMarkerElement = new MarkerElementClass();
                ISimpleMarkerSymbol pMarkerSymbol = new SimpleMarkerSymbol();
                pMarkerSymbol.Size = 6;
                IElement pElement;
                pElement = pMarkerElement as IElement;
                pElement.Geometry = pPoint;
                pMarkerElement.Symbol = pMarkerSymbol;


                //建立文字符号对象，并设置相应的属性
                ITextElement pTextEle;
                IElement pEles;
                pTextEle = new TextElementClass();
                pTextEle.Text = "[" + XPoint + "," + YPoint + "]";
                //symbol
                ITextSymbol pTextSymbol = new TextSymbol();
                pTextSymbol.Color = GetRGBColor(255, 0, 0);
                pTextSymbol.Size = 10;
                pTextEle.Symbol = pTextSymbol;
                pEles = pTextEle as IElement;
                pEles.Geometry = pPoint;


                IGraphicsContainer pGraphicsContainer = main.axMapControl1.ActiveView as IGraphicsContainer;
                pGraphicsContainer.AddElement((IElement)pEles, 0);
                pGraphicsContainer.AddElement((IElement)pMarkerElement, 0);
                pActiveView.Refresh();

            }
        }
        #endregion
        #region 添加点元素
        private void axMapControl1Point(string lineNa)
        {
            FormMain main = (FormMain)this.Owner;
            List<CPoint> list = getPoints(lineNa);
            for (int i = 0; i < list.Count; i++)
            {

                double XPoint = list[i].lng;
                double YPoint = list[i].lat;
                IMap pMap = main.axMapControl1.Map;
                IActiveView activeView = main.axMapControl1.ActiveView;
                IPoint pPoint = new ESRI.ArcGIS.Geometry.Point();
                pPoint.PutCoords(XPoint, YPoint);
                IMarkerElement pMarkerElement = new MarkerElementClass();
                ISimpleMarkerSymbol pMarkerSymbol = new SimpleMarkerSymbol();
                pMarkerSymbol.Color = GetRGBColor(11, 200, 145);
                pMarkerSymbol.Size = 20;
                pMarkerSymbol.Style = esriSimpleMarkerStyle.esriSMSDiamond;
                IElement pElement = (IElement)pMarkerElement;
                pElement.Geometry = pPoint;
                pMarkerElement.Symbol = pMarkerSymbol;
                IGraphicsContainer pGraphicsContainer = (IGraphicsContainer)pMap;
                pGraphicsContainer.AddElement((IElement)pMarkerElement, 0);
                activeView.PartialRefresh(esriViewDrawPhase.esriViewGraphics, null, null);


            }
        }

        #endregion
        #region 取点
        private List<CPoint> getPoints(string lineNa)
        {

            DataBaseConnection connection = new DataBaseConnection();
            OleDbConnection conn = connection.getConnection();
            //创建命令
            //OleDbCommand cmd = conn.CreateCommand();

            List<CPoint> pList = new List<CPoint>();



            OleDbDataAdapter da = new OleDbDataAdapter("select * from point where 测线名称='" + lineNa + "'", conn);
            //建立适配器，通过SQL语句去搜索数据库
            DataSet ds = new DataSet();
            //建立数据集
            da.Fill(ds, "point");

            //用FILL的方式将适配器已经连接好的数据表填充到数据集MYDS这张表                 //用显示控件来显示表
            foreach (DataRow var in ds.Tables["point"].Rows)           //set.Tables[0].Rows 找到指定表的所有行 0这里可以填表名
            {
                CPoint cp = new CPoint();
                // cp.lineN = var[1].ToString();
                cp.pileN = Convert.ToDouble(var[2]);
                cp.lng = Convert.ToDouble(var[3]);
                cp.lat = Convert.ToDouble(var[4]);
                cp.count = ds.Tables["point"].Rows.Count;
                pList.Add(cp);

            }
            return pList;
        }
        #endregion
        #region 画线
        private List<CPoint> newLine(string lineNa)
        {
            FormMain main = (FormMain)this.Owner;
            List<CPoint> list = getPoints(lineNa);
            for (int i = 0; i < list.Count - 1; i++)
            {

                double XPoint = list[i].lng;
                double YPoint = list[i].lat;
                double XPoint2 = list[i + 1].lng;
                double YPoint2 = list[i + 1].lat;
                IActiveView pActiveView = main.axMapControl1.ActiveView;//定义了数据显示

                //画线
                IPoint lPoint1 = new ESRI.ArcGIS.Geometry.Point();
                lPoint1.PutCoords(XPoint, YPoint);

                IPoint lPoint2 = new ESRI.ArcGIS.Geometry.Point();
                lPoint2.PutCoords(XPoint2, YPoint2);
                IPolyline mpLine = CreatePolyLineByTwoPoint(lPoint1, lPoint2);
                ILineElement lineElement = new LineElementClass();

                ISimpleLineSymbol pSLS = new SimpleLineSymbol();
                IRgbColor pColor = GetRGBColor(0, 255, 0);
                pSLS.Color = pColor;
                pSLS.Width = 2;
                lineElement.Symbol = pSLS;

                IElement lElement = lineElement as IElement;
                lElement.Geometry = mpLine;
                //----

                IGraphicsContainer pGraphicsContainer = main.axMapControl1.ActiveView as IGraphicsContainer;


                pGraphicsContainer.AddElement((IElement)lineElement, 0);

                pActiveView.Refresh();


            }

            return list;
        }
        #endregion
        #region 根据两点生成一条线
        private IPolyline CreatePolyLineByTwoPoint(IPoint p1, IPoint p2)
        {
            INewLineFeedback m_LineFeed = new NewLineFeedback();
            m_LineFeed.Start(p1);
            m_LineFeed.AddPoint(p2);
            IPolyline m_PolyLine = m_LineFeed.Stop();
            return m_PolyLine;
        }
        #endregion
        #region 调颜色
        private IRgbColor GetRGBColor(int red, int green, int blue)
        {
            IRgbColor rGBColor = new RgbColor();
            rGBColor.Red = red;
            rGBColor.Green = green;
            rGBColor.Blue = blue;
            return rGBColor;
        }
        #endregion        

　　

C：泛型的使用

把数据存入泛型之后。想要调用直接遍历个数取出调用的参数名字就好。详细看上代码