利用地图图层的属性项填充下拉列表

 

private   void  FillDropDown( string  tableName,  string  colName, string  startPoint,  string  startPointName) 
         {
            MapInfo.Mapping.Map map = null;

            if (MapInfo.Engine.Session.Current.MapFactory.Count == 0||(map = MapInfo.Engine.Session.Current.MapFactory[0]) == null)
            {
                return;
            }

            DropDownList2.Items.Clear();
            MapInfo.Mapping.FeatureLayer fl2 = (MapInfo.Mapping.FeatureLayer)map.Layers[tableName];
            MapInfo.Data.Table  t2 = fl2.Table;
            MIDataReader tr2;
            MIConnection con2 = new MIConnection();
            MICommand tc2 = con2.CreateCommand();
            tc2.CommandText = "select " + colName + " from " + t2.Alias ;
            con2.Open();
            tr2 = tc2.ExecuteReader() ;
            while (tr2.Read()) 
            {
                DropDownList2.Items.Add(tr2.GetString(0));

            }
            tc2.Cancel();
            tc2.Dispose();
            tr2.Close() ;
            con2.Close();

            DropDownList1.Items.Clear();
            MapInfo.Mapping.FeatureLayer fl1 = (MapInfo.Mapping.FeatureLayer)map.Layers[startPoint];
            MapInfo.Data.Table  t1 = fl1.Table;
            MIDataReader tr1;
            MIConnection con1= new MIConnection();
            MICommand tc1 = con1.CreateCommand();
            tc1.CommandText = "select " + startPointName + " from " + t1.Alias ;
            con1.Open();
            tr1 = tc1.ExecuteReader() ;
            while (tr1.Read()) 
            {
                DropDownList1.Items.Add(tr1.GetString(0));

            }
            tc1.Cancel();
            tc1.Dispose();
            tr1.Close();
            con1.Close();

        }