后台代码：

    /// <summary>        /// 绑定下拉菜单        /// </summary>        private void BindDropList()        {            DataTable dt = bacManage.GetAllArticleCategory();            CreateLevelDropDown(drpCategoryId, dt);        }        /// <summary>        /// 创建分级下拉框        /// </summary>        /// <param name="ddlst"></param>        /// <param name="dt"></param>        private void CreateLevelDropDown(DropDownList ddlst, DataTable dt)        {            System.Collections.ArrayList allItems = new ArrayList();            DataRow[] rows = dt.Select("[parent]=" + 0);            foreach (DataRow row in rows)                CreateLevelDropDownAssistant(dt, ref   allItems, row, string.Empty);            ListItem[] items = new ListItem[allItems.Count];            allItems.CopyTo(items);            ddlst.Items.AddRange(items);        }        /// <summary>        /// 设置下拉列表分级格式        /// </summary>        /// <param name="dt"></param>        /// <param name="items"></param>        /// <param name="parentRow"></param>        /// <param name="curHeader"></param>        private void CreateLevelDropDownAssistant(DataTable dt, ref   ArrayList items, DataRow parentRow, string curHeader)        {            ListItem newItem = new ListItem(curHeader + parentRow["name"].ToString(), parentRow["category_id"].ToString());            items.Add(newItem);            parentRow.Delete();            DataRow[] rows = dt.Select("[parent]=‘" + newItem.Value + "‘");            for (int i = 0; i < rows.Length - 1; i++)                CreateLevelDropDownAssistant(dt, ref   items, rows[i], curHeader.Replace("┣", "|").Replace("┗", "┣") + "┣");            if (rows.Length > 0)                CreateLevelDropDownAssistant(dt, ref   items, rows[rows.Length - 1], curHeader.Replace("┣", "┃").Replace("┗", "┣") + "┗");        }

    /// <summary>
        /// 绑定下拉菜单
        /// </summary>
        private void BindDropList()
        {
            DataTable dt = bacManage.GetAllArticleCategory();
            CreateLevelDropDown(drpCategoryId, dt);
        }

        /// <summary>
        /// 创建分级下拉框
        /// </summary>
        /// <param name="ddlst"></param>
        /// <param name="dt"></param>
        private void CreateLevelDropDown(DropDownList ddlst, DataTable dt)
        {
            System.Collections.ArrayList allItems = new ArrayList();
            DataRow[] rows = dt.Select("[parent]=" + 0);
            foreach (DataRow row in rows)
                CreateLevelDropDownAssistant(dt, ref   allItems, row, string.Empty);

            ListItem[] items = new ListItem[allItems.Count];
            allItems.CopyTo(items);
            ddlst.Items.AddRange(items);
        }

        /// <summary>
        /// 设置下拉列表分级格式
        /// </summary>
        /// <param name="dt"></param>
        /// <param name="items"></param>
        /// <param name="parentRow"></param>
        /// <param name="curHeader"></param>
        private void CreateLevelDropDownAssistant(DataTable dt, ref   ArrayList items, DataRow parentRow, string curHeader)
        {
            ListItem newItem = new ListItem(curHeader + parentRow["name"].ToString(), parentRow["category_id"].ToString());
            items.Add(newItem);
            parentRow.Delete();

            DataRow[] rows = dt.Select("[parent]=‘" + newItem.Value + "‘");
            for (int i = 0; i < rows.Length - 1; i++)
                CreateLevelDropDownAssistant(dt, ref   items, rows[i], curHeader.Replace("┣", "|").Replace("┗", "┣") + "┣");

            if (rows.Length > 0)
                CreateLevelDropDownAssistant(dt, ref   items, rows[rows.Length - 1], curHeader.Replace("┣", "┃").Replace("┗", "┣") + "┗");
        }