树的应用

介绍:
http://www.microsoft.com/china/community/Column/30.mspx

http://www.microsoft.com/china/community/Column/21.mspx

http://renyu732.cnblogs.com/archive/2005/06/28/182553.html

/**//// <summary>
        /// 根据岗位ID获取上级岗位ID号。
        /// </summary>
        /// <param name="job_id">岗位ID</param>
        /// <returns></returns>
        public static string GetParentIDStr(string job_id)
        {
            
            string StrSql="select parentid from sx_job where idno="+job_id;
            DBConnect dc=new DBConnect();
            string Parentid=dc.GetFieldValue(StrSql);
            dc.Close();

            if(Parentid==""||Parentid=="0")
            {
                return "0";
            }
            else
            {
                return Parentid+","+GetParentIDStr(Parentid);

            }            
            return null;
        }
    
        /**//// <summary>
        /// 根据岗位ID获取下级岗位ID号。
        /// </summary>
        /// <param name="job_id"></param>
        /// <returns></returns>
        public static string GetChildIDStr(string job_id)
        {
            if(job_id==""||job_id=="0") return null;
            string StrSql="select idno from sx_job where parentid="+job_id;
            DBConnect dc=new DBConnect();
            DataTable dt=new DataTable();
            dt=dc.GetDtBySql(StrSql);
            dc.Close();

            if(dt.Rows.Count==0)
            {
                return null;
            }
            else
            {
                string ListStr=string.Empty;
            
                for(int i=0;i<dt.Rows.Count;i++)
                {
                    string child=dt.Rows[i]["idno"].ToString();
                    
                    ListStr+= child+","+GetChildIDStr(child);
                }
                return ListStr;
            }
            return null;
        }