Re: Time stamp diff function
- From: Kim Berg Hansen <kibeha@xxxxxxxxx>
- To: andrew.kerber@xxxxxxxxx
- Date: Fri, 7 Nov 2014 18:09:42 +0100
Hi, Andres
We have NUMTODSINTERVAL, but not DSINTERVALTONUM, sadly.
So a function like you make is probably needed, I think.
A couple small things I can think of:
1) There's a lot of repetition of code.
2) Why select from dual?
Point 1 makes not much difference performance wise.
Point 2 makes unnecessary context switches between SQL and PL/SQL and can
make a bit of performance difference.
My take on a rewrite would be:
create or replace function tsdiff(ts1 in timestamp, ts2 in timestamp, units
in varchar2)
/* units - l=millisecond s=second, m=minute, h=hour, d=day */
return number
is
diff interval day(9) to second(9) := ts1 - ts2;
begin
return (
extract(day from diff)
+ extract(hour from diff)/24
+ extract(minute from diff)/24/60
+ extract(second from diff)/24/60/60
) * case (lower(units))
when 'l' then 24*60*60*1000
when 's' then 24*60*60
when 'm' then 24*60
when 'h' then 24
when 'd' then 1
else null
end;
end;
/
There can be other rewrites that also would be fine, but this works on an
11.2 instance (at least with a few tests I made :-)
I am not quite sure - but perhaps the select from dual trick might be
necessary on old versions, as PL/SQL didn't always have all SQL functions -
maybe EXTRACT used to only SQL? I am not stating that for certain, but
maybe...
Regards
Kim Berg Hansen
http://dspsd.blogspot.com
kibeha@xxxxxxxxx
@kibeha
On Fri, Nov 7, 2014 at 3:41 PM, Andrew Kerber <andrew.kerber@xxxxxxxxx>
wrote:
> I don't typically work with time intervals a lot, so I am not really
> familiar with getting a difference between timestamps. I wrote the function
> below to subtract two timestamps. Does anyone have a better example of how
> to do this:
>
> create or replace function tsdiff(ts1 in timestamp, ts2 in timestamp,
> units in varchar2)
> /* units - l=millisecond s=second, m=minute, h=hour, d=day */
> return number
> is
> diffval number;
> unitsin char(1);
> begin
> unitsin:=lower(units);
> if unitsin='l'
> then
> select
> extract(day from (ts1-ts2))*24*60*60*1000
> + extract(hour from (ts1-ts2))*60*60*1000
> + extract(minute from (ts1-ts2))*60*1000
> + extract(second from (ts1-ts2))*1000
> into diffval
> from dual;
> elsif unitsin='s'
> then
> select
> extract(day from (ts1-ts2))*24*60*60
> + extract(hour from (ts1-ts2))*60*60
> + extract(minute from (ts1-ts2))*60
> + extract(second from (ts1-ts2))
> into diffval
> from dual;
> elsif unitsin='m'
> then
> select
> extract(day from (ts1-ts2))*24*60
> + extract(hour from (ts1-ts2))*60
> + extract(minute from (ts1-ts2))
> + extract(second from (ts1-ts2))/60
> into diffval
> from dual;
> elsif unitsin='h'
> then
> select
> extract(day from (ts1-ts2))*24
> + extract(hour from (ts1-ts2))
> + extract(minute from (ts1-ts2))/60
> + extract(second from (ts1-ts2))/60/60
> into diffval
> from dual;
> elsif unitsin='d'
> then
> select
> extract(day from (ts1-ts2))
> + extract(hour from (ts1-ts2))/24
> + extract(minute from (ts1-ts2))/24/60
> + extract(second from (ts1-ts2))/24/60/60
> into diffval
> from dual;
> end if;
> return diffval;
> end;
>
> Sent from my iPad--
> //www.freelists.org/webpage/oracle-l
>
>
>
Other related posts:
