Query returning wrong results - Help required.

Question

Hi All,
I am having a query in which I have 10 records, 5 with stop time 1 and 5 with stop time 2.
I have a scenario in which, I need to calculate the maximum,minimum for the records
with stop time 1 and 2.
What I did is, I selected all the 10 records using for loop. Within the loop
I am trying to find the maximum and minimum. It is giving me wrong results.
Please help me. My code is follows
declare
     v_p1_min_stop_tm     number;
     v_p1_max_stop_tm     number;
     v_p2_min_stop_tm     number;
     v_p2_max_stop_tm     number;
begin
     for i in(
          select
               stop_tm
          from
               sample_stop
          where
               map_nbr = 16645 and
               stop_dt = '05-sep-08'
     )loop
          if i.stop_tm = 1 then
               select
                    min(i.stop_tm),
                    max(i.stop_tm)
               into
                    v_p1_min_stop_tm,
                    v_p1_max_stop_tm
               from
                    dual;
          elsif i.stop_tm = 2 then
               select
                    min(i.stop_tm),
                    max(i.stop_tm)
               into
                    v_p2_min_stop_tm,
                    v_p2_max_stop_tm
               from
                    dual;
          end if;
     end loop;
     dbms_output.put_line('minimum p1 stop time : '|| v_p1_min_stop_tm);
     dbms_output.put_line('maximum p1 stop time : '|| v_p1_max_stop_tm);
     dbms_output.put_line('minimum p2 stop time : '|| v_p2_min_stop_tm);
     dbms_output.put_line('maximum p2 stop time : '|| v_p2_max_stop_tm);
end;
My o/p is :
Minimum P1 stop time : 523
Maximum P1 stop time : 523
Minimum P2 stop time : 719
Maximum P2 stop time : 719
Here how can I make the data as two sets, one set with stop time 1 and
other with stop time 2.
Regards
Raghu

Answer 1

If the data type of stop_tm is varchar then try following
declare
     v_p1_min_stop_tm number;
     v_p1_max_stop_tm number;
     v_p2_min_stop_tm number;
     v_p2_max_stop_tm number;
begin
     for i in(select  stop_tm  from  sample_stop
          where
               map_nbr = 16645 and
               stop_dt = '05-sep-08'
          )loop
     if i.stop_tm = 1 then
          select min(to_number(i.stop_tm)), max(to_number(i.stop_tm))
               into v_p1_min_stop_tm,v_p1_max_stop_tm
          from
               dual;
     elsif i.stop_tm = 2 then
          select
               min(to_number(i.stop_tm)),     max(to_number(i.stop_tm))
               into
               v_p2_min_stop_tm,v_p2_max_stop_tm
          from
               dual;
     end if;
end loop;
dbms_output.put_line('minimum p1 stop time : '|| v_p1_min_stop_tm);
dbms_output.put_line('maximum p1 stop time : '|| v_p1_max_stop_tm);
dbms_output.put_line('minimum p2 stop time : '|| v_p2_min_stop_tm);
dbms_output.put_line('maximum p2 stop time : '|| v_p2_max_stop_tm);
end;
/ Regards
Singh