oracle存储过程动态条件以及游标问题。

create or replace procedure stat_centeruserstatistic_sp(
                                                        i_orgno_no       in sunds.bp_centeruserstatistic_tb.organ_no%type, --处理中心
                                                        i_flow_node      in sunds.bp_centeruserstatistic_tb.flow_node%type, --节点名称
                                                        i_user_no        in sunds.bp_centeruserstatistic_tb.user_no%type, --柜员号
                                                        i_trans_id       in sunds.bp_centeruserstatistic_tb.trans_id%type, --业务种类
                                                        i_reportFormType in varchar2, --报表类型；0：日，1：月，2：年，3：时段
                                                        i_date           in sunds.bp_centeruserstatistic_tb.stat_date%type, --日期
                                                        i_startdate      in sunds.bp_centeruserstatistic_tb.stat_date%type, -- 时段起始日期
                                                        i_enddate        in sunds.bp_centeruserstatistic_tb.stat_date%type, --时段终止日期
                                                        I_PAGE_IDX       in varchar2, --页码
                                                        cur              out sys_refcursor,
                                                        O_RET            out varchar2,
                                                        O_MSG            out varchar2) is
v_sql_where_str varchar(4000);     
v_sql varchar(4000);                                     
begin      --日统计
  if(i_reportFormType='0') then
    v_sql_where_str := ' select t.flow_node as flow_node, 
              t.user_no as user_no,
              t.trans_id as trans_id,
              sum(t.count)as all_together,
              sum(decode(t.stat_flag,''01'',t.count,0))as suc_count,
              sum(decode(t.stat_flag,''00'',t.count,0))as non_count,
              round(sum(decode(t.stat_flag,00, t.count,0))/sum(t.count)*100,2)   as non_proba,
              round(sum(t.con_time) / sum(t.count),2) as avg_times
       from sunds.bp_centeruserstatistic_tb t
       where  t.organ_no= '||chr(39)||i_orgno_no||chr(39)
       ||'and t.stat_date='||chr(39)||i_date||CHR(39);
       
  if i_flow_node is not null then
    v_sql_where_str := v_sql_where_str ||'and t.flow_node ='||
    chr(39) || i_flow_node || chr(39);
  end if;
  if i_user_no is not null then
    v_sql_where_str := v_sql_where_str || 'and t.user_no ='||
    chr(39) || i_user_no ||chr(39);
  end if;
  if i_trans_id is not null then 
    v_sql_where_str := v_sql_where_str ||' and t.trans_id ='||
    chr(39) || i_trans_id ||chr(39);
  end if;
  v_sql_where_str := v_sql_where_str ||'group by t.user_no,t.flow_node,t.trans_id
       order by t.flow_node,t.user_no;';
        --dbms_output.put_line('v_sql_where_str:'|| v_sql_where_str);
        open cur for v_sql_where_str;
        O_RET := '0';
        O_MSG := '查询成功';
    end if;
exception
  when others then
    O_RET := 'SP01000';
    O_MSG := '查询失败';
end stat_centeruserstatistic_sp;
/
经调试，总是在open这块跑异常，不知道什么原因，求高手指点下，本人也才学的存储过程谢谢