Can I ADD using a TIMESTAMP ???

Question

here is an example and wondering if this is possible
Selct EMP_NUM,
SUM("DSS_SNOW_PROGRAM"."TIME_OUT" - "DSS_SNOW_PROGRAM"."TIME_IN") as "HOURS_WORKED"
FROM DRIVERS_LOG
WHERE EMP_NUM='2'
AND TO_DATE(TO_CHAR("DSS_SNOW_PROGRAM"."TIME_IN", 'DD-MON-YY')) BETWEEN '01-DEC-10' AND '07-DEC-10'
Is it possible to add up the total hours emp 2 worked from 01-dec-10 to 07-dec-10??
how can i achieve the correct syntax???
Thanks for the help and assistance.

Answer 1

NOT TESTED! something to play with (datatype date used instead of timestamp to keep lines shorter ;) )
with drivers_log as
(select 1 emp_num,to_date('01-DEC-10 8:30:40','dd-MON-rr hh24:mi:ss') time_in,to_date('01-DEC-10 16:33:44','dd-MON-rr hh24:mi:ss') time_out from dual union all
select 1,to_date('02-DEC-10 8:25:11','dd-MON-rr hh24:mi:ss'),to_date('02-DEC-10 16:32:55','dd-MON-rr hh24:mi:ss') from dual union all
select 1,to_date('03-DEC-10 8:15:22','dd-MON-rr hh24:mi:ss'),to_date('03-DEC-10 16:30:44','dd-MON-rr hh24:mi:ss') from dual union all
select 1,to_date('04-DEC-10 8:35:07','dd-MON-rr hh24:mi:ss'),to_date('04-DEC-10 16:28:12','dd-MON-rr hh24:mi:ss') from dual union all
select 1,to_date('05-DEC-10 8:29:47','dd-MON-rr hh24:mi:ss'),to_date('05-DEC-10 16:48:52','dd-MON-rr hh24:mi:ss') from dual union all
select 2,to_date('06-DEC-10 8:01:02','dd-MON-rr hh24:mi:ss'),to_date('06-DEC-10 16:58:42','dd-MON-rr hh24:mi:ss') from dual union all
select 1,to_date('07-DEC-10 8:21:33','dd-MON-rr hh24:mi:ss'),to_date('07-DEC-10 16:31:46','dd-MON-rr hh24:mi:ss') from dual union all
select 2,to_date('07-DEC-10 8:22:57','dd-MON-rr hh24:mi:ss'),to_date('07-DEC-10 16:32:55','dd-MON-rr hh24:mi:ss') from dual
select emp_num,trunc(24 * sum(time_out - time_in)) hours_worked
  from drivers_log
where time_in between to_date('01-DEC-10','dd-MON-rr') and to_date('08-DEC-10','dd-MON-rr')
group by emp_numRegards
Etbin