Very dificult query for me- need help

Question

I have table first column is time( Timestamp) ,
second column is record_num( int )
Now I need get data table for every day 8:00am to previous day 20:00pm, sum(record_num).
How can I do the query.
Thanks for your time and help
original table like
time record_num
03 27 2006 07:32:03 2
03 27 2006 06:20:08 5
03 26 2006 23:30:01 1
03 26 2006 20:00:01 7
03 25 2006 23:00:20 7
wanted query result table
03 27 2006 1234
03 26 2006 3452
or only 1234, 3452......
since I need avg( )
Thanks again

Answer 1

I am not sure exactly what you want, but it seems that if a record has a time after 22:00 then it should be included on the next day. And any records that are not between 8:00am and 8:00pm on the previous day should not be reported on. Is this what you are after?
Here is some code to achieve that:
control@DWDEV> create table my_data (my_time timestamp, my_value number);
Table created.
control@DWDEV>
control@DWDEV> -- This row should be included as it is at 1:00am
control@DWDEV> insert into my_data values (to_date('20060328010000','YYYYMMDDHH24MISS'), 1000);
1 row created.
control@DWDEV> -- This row won't be included because it is at 9:00am and not between 8am and 8pm on previous day
control@DWDEV> insert into my_data values (to_date('20060328090000','YYYYMMDDHH24MISS'), 2000);
1 row created.
control@DWDEV> -- This row should be included on the 29th because it is at 10:00pm on previous day
control@DWDEV> insert into my_data values (to_date('20060328220000','YYYYMMDDHH24MISS'), 3000);
1 row created.
control@DWDEV> -- This row should be included on the 29th because it is at 07:00am on same day
control@DWDEV> insert into my_data values (to_date('20060329070000','YYYYMMDDHH24MISS'), 400);
1 row created.
control@DWDEV> -- This row won't be included due to the time of 1:00pm
control@DWDEV> insert into my_data values (to_date('20060328130000','YYYYMMDDHH24MISS'), 600);
1 row created.
control@DWDEV>
control@DWDEV> select from8to8, sum(my_value)
  2  from
  3  (
  4     select case
  5               when to_char(my_time, 'HH24') >= 20
  6                  then to_char(my_time + 1, 'DD-MON-YYYY')
  7               when to_char(my_time, 'HH24') < 8
  8                  then to_char(my_time, 'DD-MON-YYYY')
  9               else
10                  NULL
11            end as from8to8,
12            my_value
13     from   my_data
14     where  to_char(my_time, 'HH24') < 8
15     or     to_char(my_time, 'HH24') >= 20
16  )
17  group by from8to8;
FROM8TO8    SUM(MY_VALUE)
28-MAR-2006          1000
29-MAR-2006          3400Hope that gives you a few ideas on how to achieve what you need.
Cheers,
Jeff.