How to eliminate non-working hours in Oracle

Question

I have two columns of DateTime type. The first one stores the DateTime when a process it started, the other one stores the DateTime when that process is finished. I want to

Answer 1

If i understand correctly, you want to calculate the difference between the start and finish date excluding the time before 10 am and after 7 pm.

Here's the sample query and sql fiddle.

SELECT start_time,
       finish_time,
       interval_time,
       EXTRACT (HOUR FROM interval_time), --extract the hours,mins and seconds from the interval
       EXTRACT (MINUTE FROM interval_time),
       EXTRACT (SECOND FROM interval_time)
  FROM (SELECT start_time,
               finish_time,
               NUMTODSINTERVAL (
                    CASE
                       WHEN finish_time - TRUNC (finish_time) > (19 / 24) --if finish time is after 7pm
                       THEN
                          TRUNC (finish_time) + (19 / 24)      --set it to 7pm
                       ELSE
                          finish_time      --else set it to actual finish time
                    END
                  - CASE
                       WHEN start_time - TRUNC (start_time) < (10 / 24) --if start time is before 10 am
                       THEN
                          TRUNC (start_time) + (10 / 24)    --set it to 10 am.
                       ELSE
                          start_time    --else set it to the actual start time
                    END,
                  'day') --subtract the both and convert the resulting day to interval
                  interval_time
          FROM timings);

What I have done is,

• Check if the start time is before 10 am and finish time is after 7 pm. If so, set the time to 10 am and 7 pm.
• Then subtract the dates and convert the resulting days to Interval Type.
• Then extract the hours, mins and seconds from the Interval.

Note: This query assumes that both dates fall on same day and both are not before 10am or after 7 pm.

UPDATE: To exclude holidays, the query will become complicated. I suggest writing three functions and use these functions in the query.

1st function:

FUNCTION modify_start_time (p_in_dte DATE) RETURN DATE
----------------------------------
IF p_in_dte - TRUNC (p_in_dte) < (10 / 24)
THEN
   RETURN TRUNC (p_in_dte) + (10 / 24);
ELSIF p_in_dte - TRUNC (p_in_dte) > (19 / 24)
THEN
   RETURN TRUNC (p_in_dte) + 1 + (10 / 24);
ELSE
   RETURN p_in_dte;
END IF;

If the start time is outside the work hours, modify the start time to next nearest start time.

2nd function:

FUNCTION modify_finish_time (p_in_dte DATE) RETURN DATE
----------------------------------
IF p_in_dte - TRUNC (p_in_dte) > (19 / 24)
THEN
   RETURN TRUNC (p_in_dte) + (19 / 24);
ELSIF p_in_dte - TRUNC (p_in_dte) < (10 / 24)
THEN
   RETURN TRUNC (p_in_dte) - 1 + (19 / 24);
ELSE
   RETURN p_in_dte;
END IF;

If the finish time is outside the work hours, modify it to the previous nearest finish time.

3rd function:

FUNCTION get_days_to_exclude (p_in_start_date     DATE,
                              p_in_finish_date    DATE) RETURN NUMBER
--------------------------------------------------------
WITH cte --get all days between start and finish date
     AS (    SELECT p_in_start_date + LEVEL - 1 dte
               FROM DUAL
         CONNECT BY LEVEL <= p_in_finish_date + 1 - p_in_starT_date)
SELECT COUNT (1) * 9 / 24    --mutiply the days with work hours in a day
  INTO l_num_holidays
  FROM cte
 WHERE    TO_CHAR (dte, 'dy') = 'sun'    --find the count of sundays
       OR dte IN     --fins the count of holidays, assuming leaves are stored in separate table
             (SELECT leave_date  
                FROM leaves
               WHERE leave_date BETWEEN p_in_start_date
                                    AND p_in_finish_date);

l_num_holidays :=
   l_num_holidays + ( (p_in_finish_date - p_in_start_date) * (15 / 24)); --also, if the dates span more than a day find the non working hours.

RETURN l_num_holidays;

This function finds the no of days to be excluded while calculating the duration.

So, the final query should be something like this,

SELECT start_time,
       finish_time,
       CASE
          WHEN work_duration < 0 THEN NUMTODSINTERVAL (0, 'day')
          ELSE NUMTODSINTERVAL (work_duration, 'day')
       END
  FROM (SELECT start_time, finish_time,
               --modify_start_time (start_time), modify_finish_time (finish_time),
                 modify_finish_time (finish_time)
               - modify_start_time (start_time)
               - get_days_to_exclude (
                    TRUNC (modify_start_time (start_time)),
                    TRUNC (modify_finish_time (finish_time)))
                  work_duration
          FROM timings);

If the duration is less than 0, ignore it by setting it to 0.

Answer 2

You can take the hour difference between the two dates and reduce the amount of non-working hours times the days between the two days. consider this example :

create table t1 (
    start_hour date , finish_hour date);

insert into t1 values (
  to_date('01/01/2013 12:00:00','dd/mm/yyyy hh24:mi:ss'),
  to_date('01/01/2013 15:00:00','dd/mm/yyyy hh24:mi:ss'));

insert into t1 values (
  to_date('01/01/2013 12:00:00','dd/mm/yyyy hh24:mi:ss'),
  to_date('02/01/2013 15:00:00','dd/mm/yyyy hh24:mi:ss'));

insert into t1 values (
  to_date('01/01/2013 18:00:00','dd/mm/yyyy hh24:mi:ss'),
  to_date('03/01/2013 11:00:00','dd/mm/yyyy hh24:mi:ss'));


with x as (
select start_hour ,finish_hour , 
      (finish_hour - start_hour) * 24 hour_diff , 
       trunc(finish_hour) - trunc(start_hour) as day_diff
from t1
) 
select  start_hour , finish_hour , 
        hour_diff - 15 * day_diff as working_hours 
from x;

|                     START_HOUR |                    FINISH_HOUR | WORKING_HOURS |
-----------------------------------------------------------------------------------
| January, 01 2013 12:00:00+0000 | January, 01 2013 15:00:00+0000 |             3 |
| January, 01 2013 12:00:00+0000 | January, 02 2013 15:00:00+0000 |            12 |
| January, 01 2013 18:00:00+0000 | January, 03 2013 11:00:00+0000 |            11 |