.NET中ListBox和DropDownList的数据绑定

private void Button1_Click(object sender, System.EventArgs e)

       {

           if(ListBox1.Visible==false)

           {

              SqlConnection conn=new SqlConnection(@"Server="+DB_Host+";DataBase="+DB_Name+";uid="+DB_Uid+";pwd="+DB_Pwd+"");

              SqlDataAdapter da=new SqlDataAdapter("SELECT * from TEMP",conn);

              DataSet ds=new DataSet();

              da.Fill(ds,"UN");

              ListBox1.DataSource=ds;

              ListBox1.DataTextField="UN";

              ListBox1.DataValueField="UP";

              ListBox1.DataBind();

              ListBox1.Visible=true;

           }

           else

           {

              ListBox1.Visible=false;

           }

       }