Calculate the Sum of duration in sql query

Question

I have a table which has two columns start time and end time. I am able to calculate the time duration for each row but I also want to get the total duration. how to do this.

Thanks

Answer 1

Your columns are of datatype TIMESTAMP, like this:

SQL> create table mytable (start_time,end_time)
  2  as
  3  select to_timestamp('2009-05-01 12:34:56','yyyy-mm-dd hh24:mi:ss')
  4       , to_timestamp('2009-05-01 23:45:01','yyyy-mm-dd hh24:mi:ss')
  5    from dual
  6   union all
  7  select to_timestamp('2009-05-01 23:45:01','yyyy-mm-dd hh24:mi:ss')
  8       , to_timestamp('2009-05-02 01:23:45','yyyy-mm-dd hh24:mi:ss')
  9    from dual
 10   union all
 11  select to_timestamp('2009-05-01 07:00:00','yyyy-mm-dd hh24:mi:ss')
 12       , to_timestamp('2009-05-01 08:00:00','yyyy-mm-dd hh24:mi:ss')
 13    from dual
 14  /

Tabel is aangemaakt.

Subtracting one timestamp from another, leads to an INTERVAL datatype:

SQL> select start_time
  2       , end_time
  3       , end_time - start_time time_difference
  4    from mytable
  5  /

START_TIME                     END_TIME                       TIME_DIFFERENCE
------------------------------ ------------------------------ ------------------------------
01-05-09 12:34:56,000000000    01-05-09 23:45:01,000000000    +000000000 11:10:05.000000000
01-05-09 23:45:01,000000000    02-05-09 01:23:45,000000000    +000000000 01:38:44.000000000
01-05-09 07:00:00,000000000    01-05-09 08:00:00,000000000    +000000000 01:00:00.000000000

3 rijen zijn geselecteerd.

And INTERVAL datatypes cannot be summed. It's an annoying restriction:

SQL> select sum(end_time - start_time)
  2    from mytable
  3  /
select sum(end_time - start_time)
                    *
FOUT in regel 1:
.ORA-00932: inconsistente gegevenstypen: NUMBER verwacht, INTERVAL DAY TO SECOND gekregen

To circumvent this restriction, you can convert and calculate with the number of seconds, like this:

SQL> select start_time
  2       , end_time
  3       , trunc(end_time) - trunc(start_time) days_difference
  4       , to_number(to_char(end_time,'sssss')) - to_number(to_char(start_time,'sssss')) seconds_difference
  5    from mytable
  6  /

START_TIME                     END_TIME                       DAYS_DIFFERENCE SECONDS_DIFFERENCE
------------------------------ ------------------------------ --------------- ------------------
01-05-09 12:34:56,000000000    01-05-09 23:45:01,000000000                  0              40205
01-05-09 23:45:01,000000000    02-05-09 01:23:45,000000000                  1             -80476
01-05-09 07:00:00,000000000    01-05-09 08:00:00,000000000                  0               3600

3 rijen zijn geselecteerd.

And then they are normal NUMBERs that can be summed

SQL> select sum
  2         (  86400 * (trunc(end_time) - trunc(start_time))
  3          + to_number(to_char(end_time,'sssss')) - to_number(to_char(start_time,'sssss'))
  4         ) total_time_difference
  5    from mytable
  6  /

TOTAL_TIME_DIFFERENCE
---------------------
                49729

1 rij is geselecteerd.

And if you wish, you can convert this number back to an INTERVAL:

SQL> select numtodsinterval
  2         ( sum
  3           (  86400 * (trunc(end_time) - trunc(start_time))
  4            + to_number(to_char(end_time,'sssss')) - to_number(to_char(start_time,'sssss'))
  5           )
  6         , 'second'
  7         ) time_difference
  8    from mytable
  9  /

TIME_DIFFERENCE
------------------------------
+000000000 13:48:49.000000000

1 rij is geselecteerd.

Regards, Rob.

Answer 2

This method for Oracle is simple, a bit of a hack though:

select sum((end_timestamp+0) - (start_timestamp+0)) 
from your_table

Result is a NUMBER of days (with fractional part for hours, minutes and you know).

I don't know what timestamp + 0 does exactly; maybe the ANSI timestamp gets converted to Oracle's earlier timestamp type that allows simple arithmetic.

Answer 3

EDIT: Added trunc() before summing based on Rob van Wijk's excellent reply.

To find the duration per row:

select 
    end_date-start_date as DurationDays, 
    (end_date-start_date)*24 as DurationHours, 
    (end_date-start_date)*24*60 as DurationMinutes, 
    (end_date-start_date)*24*60*60 as DurationSeconds
from your_table

To find the total duration:

select 
    sum(trunc(end_date-start_date)) as TotalDurationDays
from your_table

To do both in one query:

select 
    end_date-start_date as DurationDays, 
    (select sum(trunc(end_date-start_date)) from your_table) as TotalDurationDays
from your_table