在动态绑定的DropDownlist的最前面加上一个空白项或“全部”

 

前端代码Html层
<asp:DropDownList id="ddltItem" runat="server" DataTextField="ItemName" DataValueField="ItemNO"></asp:DropDownList>

CS代码层
public void SelectItem(int i)
  {

   SqlConnection myConnection = new SqlConnection(ConfigurationSettings.AppSettings["ConnectionString"]);

   string mySelectQuery =
    "select ItemNO,ItemName from ts_AO_Item order by ItemNO";
   
   SqlDataAdapter myCommand = new SqlDataAdapter(mySelectQuery,myConnection);
   myConnection.Open();
   DataSet ds = new DataSet();
   myCommand.Fill(ds,"data");
   AddxmDs(ds);

    item.DataSource=ds.Tables["data"].DefaultView;
    item.DataBind();

   myConnection.Close();

  }
  private void AddxmDs(DataSet ds)
  {

   ds.Tables[0].Rows[0]["ItemNO"]="-1";
   ds.Tables[0].Rows[0]["ItemName"]="- 全部 -";

  }