DropDownList控件添加,删除操作

protected void Page_Load(object sender, EventArgs e)
    {
        //向下拉列表框中添加列表项
        if (!IsPostBack)
        {
            this.dropName.Items.Add(new ListItem("北京", "0"));
            this.dropName.Items.Add(new ListItem("上海", "1"));
            this.dropName.Items.Add(new ListItem("深圳", "2"));
            this.dropName.Items.Add(new ListItem("唐山", "3"));
        }
    }

protected void btnDelete_Click(object sender, EventArgs e)
    {
        //删除选择的列表项
        ListItem Item = dropName.SelectedItem;
        dropName.Items.Remove(Item);
    }

protected void btnDeleteAll_Click(object sender, EventArgs e)
    {
        //清除所有列表项
        dropName.Items.Clear();
    }