public void Listar()
 {
     List<Area> ar = new AreaBL().List();
     if (ar.ToList().Count() > 0)
     {
         GridView1.DataSource = ar.ToList();
         GridView1.DataBind();
     }
     else
     {
         GridView1.DataSource = null;
         GridView1.DataBind();
     }
 }
 public void ListarArea()
 {
     List<Area> ar = new AreaBL().List();
     if (ar.ToList().Count() > 0)
     {
         foreach (Area a in ar)
         {
             CboArea.Items.Add(a.Nom_area);
         }
     }
     else
     {
         CboArea.DataSource = null;
     }
 }