asked on

computing date/time difference in MS SQL

hi.

i need to create an sql statement or script that would compute the difference between dates.

here are example data in my workflow table (the data type for my dates are datetime:

step end_date start_date
------ ------------- ------------
step1 2006-10-29 15:13:27.750 2006-10-29 14:43:34.937

step2 2006-10-06 09:25:25.000 2006-10-05 08:25:20.000

i tried doing this:

select finish_date-start_date as duration from wf_historystep

but it gave me this result:

duration
-----------
1900-01-01 00:29:52.813
1900-01-02 01:00:05.000

when it should be:

duration
-----------
0 00:29:52.813 (0 day, 29 min, 52 sec and 813 millisec)
1 01:00:05.000 (1 day, 1 hr, 0 min, 5 sec and 0 millisec)

how am i going to reconstruct my sql so that my result would be:

duration
-----------
0 00:29:52.813
1 01:00:05.000

thanks in advance!

HuyBD

select datediff(millisecond,start_date,finish_date) as duration from wf_historystep

HuyBD

you can use other datepart for millisecond, e.g: day, minute, second....

get diff in millisecond, you can use divide operator to get day, munite, second...

Aneesh

For milliseconds, the maximum number is 24 days, 20 hours, 31 minutes and 23.647 seconds. For seconds, the maximum number is 68 years. So if you are sure that if you take the the datediff wont go beyond the abve mentioned values go for MilliSecond or Minute
refer books online for more options

DATEDIFF ( ms , startdate , enddate )

ASKER CERTIFIED SOLUTION

imran_fast

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

ayeen

ASKER

hi imran_fast

i like ur solution but how about for the time difference?

ayeen

ASKER

i tried to use these functions:

datepart(day, finish_date)-datepart(day, start_date) as dayctr,
datepart(hour, finish_date) - datepart(hour,start_date) as hrctr

but i get negative values for the case when the hours for the start_date is greater than the finish_date (in case of military time), like the data below:

start_date finish_date dayctr hrctr
------------- ------------- --------- -------
2006-10-28 20:42:32.037 2006-10-29 11:21:52.150 1 -9

how can i make the hrctr become 15 instead of -9? how can i do this in sql:

hrctr = hour_end - hour_start
if hrctr < 0
then duration = hrctr - 24

ex. data:
hour_end = 11
hour_start = 20

hrctr = 11 - 20
hrctr = -9
duration = -9 - 24
duration = 15

thanks again in advance!

ayeen

ASKER

hi mod,

i was able to solve this myself but i would like to give 50 points to imran_fast

here's my solution:

select
start_date as StartDate,
finish_date as EndDate,
convert(varchar(5),datepart(day, finish_date)-datepart(day, start_date)) + convert(varchar(5),datepart(hour, finish_date) - datepart(hour,start_date)) as Duration

from mytable