datatable 绑定下拉菜单

Question

我想问一下我有一个下拉菜单是datatable绑定的.请问我怎么能在下拉列表上面加一行请选择？

Answer 1

ListItem li = new ListItem("请选择","-1");;
this.DropDownList.Items.Insert(0,li);

Answer 2

             DataTable dtPp = logic.Logic();
            ddlPp.DataSource = dtPp;
            ddlPp.DataTextField = "ppmc";
            ddlPp.DataValueField = "pp_id";
            ddlPp.DataBind();
我是这样写的~用的是dropdownlist

Answer 3

             DataTable dtPp = logic.Logic();
            ddlPp.DataSource = dtPp;
            ddlPp.DataTextField = "ppmc";
            ddlPp.DataValueField = "pp_id";
            ddlPp.DataBind();
我是这样写的~用的是dropdownlist

Answer 4

把text属性改成请选择  

Answer 5

this.DropDownList.Items.Add(new ListItem("请选择","-1")) 这样默认追加到最后一项了
this.DropDownList.Items.Insert(0,new ListItem("请选择","-1"))；这样到第一的位置