protected void ddlBind()        {            DataTable dt = new DataTable();            ddlCategoryId.DataSource = getList("0", dt);            ddlCategoryId.DataTextField = "title";            ddlCategoryId.DataValueField = "id";            ddlCategoryId.DataBind();            ddlCategoryId.Items.Insert(0, new ListItem("请选择类别", "-1"));        }        public DataTable getList(string pid, DataTable list)        {            BLL.article_category bll = new BLL.article_category();            DataTable dt;            if (pid == "0")            {                dt = bll.GetList("parent_id=‘0‘").Tables[0];                list = dt.Clone();            }            else            {                dt = bll.GetList(" parent_id=‘" + pid + "‘").Tables[0];            }            if (dt.Rows.Count > 0)            {                foreach (DataRow row in dt.Rows)                {                    int layer = Convert.ToInt32(row["class_layer"].ToString());//深度                    string Title = row["title"].ToString().Trim();                    if (layer > 1)                    {                        Title = "├ " + Title;                        Title = StringOfChar(layer - 1, "　") + Title;                    }                    row["title"] = Title;                    list.ImportRow(row);                    getList(row["id"].ToString(), list);                }            }            return list;        }

/// <summary>        /// 生成指定长度的字符串,即生成strLong个str字符串        /// </summary>        /// <param name="strLong">生成的长度</param>        /// <param name="str">以str生成字符串</param>        /// <returns></returns>        public static string StringOfChar(int strLong, string str)        {            string ReturnStr = "";            for (int i = 0; i < strLong; i++)            {                ReturnStr += str;            }            return ReturnStr;        }/// <summary>        /// 获得数据列表        /// </summary>        public DataSet GetList(string strWhere)        {            StringBuilder strSql=new StringBuilder();            strSql.Append("select * ");            strSql.Append(" FROM article_category");            if(strWhere.Trim()!="")            {                strSql.Append(" where "+strWhere);            }            return OracleHelper.ExecuteDataset(strSql.ToString());        }