Re: I need a SQL... - Mailing list pgsql-general

Well, here is my output..:

DT=# create table mytable (starttime time, stoptime time);
CREATE TABLE
DT=# insert into mytable values ('10:45', '22:30');
INSERT 20746 1
DT=# insert into mytable values ('19:45', '04:30');
INSERT 20747 1
DT=# insert into mytable values ('00:00', '00:00');
INSERT 20748 1
DT=# insert into mytable values ('23:59', '00:01');
INSERT 20749 1
DT=# insert into mytable values ('00:01', '23:59');
INSERT 20750 1
DT=# select starttime,stoptime,(case when stoptime-starttime >= 0 then
stoptime-starttime else stoptime-starttime+'24 hours' end) as timediff
from mytable;
 starttime | stoptime | timediff
-----------+----------+----------
 10:45:00  | 22:30:00 | 11:45
 19:45:00  | 04:30:00 | -15:15
 00:00:00  | 00:00:00 | 00:00
 23:59:00  | 00:01:00 | -23:58
 00:01:00  | 23:59:00 | 23:58
(5 rows)

DT=#

Strange....

On Thu, 2003-09-11 at 15:25, Mattias Kregert wrote:
> Very strange indeed!
>
> This is my output.
> ------------------------------------
>
> Welcome to psql 7.3.3, the PostgreSQL interactive terminal.
>
  
> Type:  \copyright for distribution terms
>        \h for help with SQL commands
>        \? for help on internal slash commands
>        \g or terminate with semicolon to execute query
>        \q to quit
>
  
> test=# create table mytable (starttime time, stoptime time);
> CREATE TABLE
> test=# insert into mytable values ('10:45', '22:30');
> INSERT 103688 1
> test=# insert into mytable values ('19:45', '04:30');
> INSERT 103689 1
> test=# insert into mytable values ('00:00', '00:00');
> INSERT 103690 1
> test=# insert into mytable values ('23:59', '00:01');
> INSERT 103691 1
> test=# insert into mytable values ('00:01', '23:59');
> INSERT 103692 1
> test=# select starttime,stoptime,(case when stoptime-starttime >= 0 then stoptime-starttime else
stoptime-starttime+'24hours' end) as timediff from mytable; 
>  starttime | stoptime | timediff
> -----------+----------+----------
>  10:45:00  | 22:30:00 | 11:45
>  19:45:00  | 04:30:00 | 08:45
>  00:00:00  | 00:00:00 | 00:00
>  23:59:00  | 00:01:00 | 00:02
>  00:01:00  | 23:59:00 | 23:58
> (5 rows)
>
  
> test=#
> ------------------------------------
>
> As you see, it all works as it should. Can you do exactly the same and send me the complete output? If you get a
differentresult, then it's time to send in a bug report... 
>
> /Mattias
>
>
> ----- Original Message -----
> From: "Bjørn T Johansen" <btj@havleik.no>
> > Yes, I am sure, I just use copy-and-paste and I have double checked....
> > I am running on 7.3.4 but that shouldn't make any difference?
> >
> > BTJ
> >
> > On Thu, 2003-09-11 at 14:56, Mattias Kregert wrote:
> > > When i run it, it works as intended (on pg 7.3.3). Which version do you use?
> > >
> > > Are you absolutely sure you copied it exactly? You typed in '>=' and not '=', right?
> > >
> > > /Mattias
> > >
> > > ----- Original Message -----
> > > From: "Bjørn T Johansen" <btj@havleik.no>
> > > To: "Mattias Kregert" <mattias@kregert.se>
> > > Cc: <pgsql-general@postgresql.org>
> > > Sent: Thursday, September 11, 2003 3:02 PM
> > > Subject: Re: [GENERAL] I need a SQL...
> > >
> > >
> > > > Well, it's close... :)
> > > >
> > > > But it looks like the case doesn't work..
> > > > If I run your sql, the timediff is negative.
> > > >
> > > > But if I run this:
> > > > SELECT (stoptime-starttime+'24 hours') as timediff FROM mytable
> > > > the timediff has correct value..
> > > >
> > > > Do you see any error in the case, cause I don't?
> > > >
> > > >
> > > > BTJ
> > > >
> > > > On Thu, 2003-09-11 at 14:29, Mattias Kregert wrote:
> > > > > Solution:
> > > > >
> > > > > SELECT starttime, stoptime, (CASE WHEN stoptime-starttime >= 0 THEN
> > > > > stoptime-starttime ELSE stoptime-starttime+'24 hours' END) as timediff
> > > > > FROM mytable;
> > > > >
> > > > > /Mattias
> > > > >
> > > > >         ----- Original Message -----
> > > > >         From: Bjørn T Johansen
> > > > >         To: Andrew L. Gould
> > > > >         Cc: PostgreSQL general list
> > > > >         Sent: Thursday, September 11, 2003 2:12 PM
> > > > >         Subject: Re: [GENERAL] I need a SQL...
> > > > >
> > > > >         On Thu, 2003-09-11 at 14:07, Andrew L. Gould wrote:
> > > > >         > On Thursday 11 September 2003 06:25 am, Bjørn T Johansen wrote:
> > > > >         > > I need to write a SQL that calculates the interval between a start time
> > > > >         > > and a stop time. This is the easy part. The problem is that I only have
> > > > >         > > the time part, i.e. no date, so how can I be sure to also calculate the
> > > > >         > > interval if the start time is before midnight and the stop time is after
> > > > >         > > midnight?
> > > > >         > >
> > > > >         > >
> > > > >         > > Regards,
> > > > >         > >
> > > > >         > > BTJ
> > > > >         >
> > > > >         > If the activity or period you are measuring can equal or exceed 12 hours, you
> > > > >         > won't be able to calculate it reliably without a start date and a stop date.
> > > > >         > If the periods are always less than 12 hours (and you assume all the data is
> > > > >         > good), then stop times that are less than start times would indicate an
> > > > >         > intervening midnight.
> > > > >         >
> > > > >         > The dates do not have to be in the same fields as the times, since you can add
> > > > >         > date and time data to create a timestamp for datetime calculations:
> > > > >         >
> > > > >         > (stop_date + stop_time) - (start_date + start_time)
> > > > >         >
> > > > >         > Best of luck,
> > > > >         >
> > > > >         > Andrew Gould
> > > > >
> > > > >
> > > > >
> > > > >         Yes, the period can exceed 12 hours, so what you are saying is that this is not possible to solve
> > > > >         without the date part? I can write this logic in my business logic but I was hoping to
> > > > >         solve this in my database layer...
> > > > >
> > > > >
> > > > >         BTJ
> > > >
> > > >
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> > --
> > -----------------------------------------------------------------------------------------------
> > Bjørn T Johansen (BSc,MNIF)
> > Executive Manager
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