Re: How to convert Oracle Database Date Type to C time_t

but is there time_t date type in pro*C? I got the code from this forum, is it because I didn't include some header filer?

In article <37BCA9E8.1EC8_at_swbell.net>,
  mck9_at_swbell.net wrote:
> Michel Cadot wrote:
> >
> > Ellen,
> >
> > I think you're wrong with operations on date type.
> > Your select can be (t as long):
> > select
> > to_number( to_char(datecol,'J'))*24*60*60+to_number(to_char
(datecol,'SSSSS')) -
> > (to_number(to_char(to_date
('01/01/1970','DD/MM/YYYY'),'J'))*24*60*60
> > +to_number(to_char(to_date
('01/01/1970','DD/MM/YYYY'),'SSSSS')) )
> > into :t
> > from ...;
> >
> > This gives you the number of seconds since 01/01/1970.
> > Has time_t type a particuliar structure?
>
> No. The encoding you describe is common, but it is not required by
> the C Standard, which requires only that a time_t be an arithmetic
> type capable of representing times. For example it could be a long
> double representing the number of days since the birth of Brian
> Kernighan (one of the co-inventors of C).
>
> As a result there's no way that Oracle could reliably map a date type
> to a time_t for all environments.
>
> The simplest and most portable way to do the translation is: let
> Oracle format the date and time into the various components of a
> struct tm and then call mktime().
>
> Scott McKellar mck9_at_swbell.net
> Free PL/SQL utilities at http:://home.swbell.net/mck9/pls/
>
> > ellen111_at_my-deja.com a écrit dans le message <7pgnl5
$kgj$1_at_nnrp1.deja.com>...
> > >Hi, when I try to retrieve date from oracle database, and convert
it
> > >to time_t type, I have some questions.
> > >
> > >the way now I used is:
> > >select date into char from oracle database, then convert char
> > >to time_t(I wrote a function by myself). and it is not very
efficient.
> > >
> > >I was told that there is a way to convert them directly:
> > >select date into time_t(? or long, because there is no time_t date
> > >type in pro*C), following is my code:
> > >
> > >EXEC SQL BEGIN DECLARE SECTION;
> > >time_t t; //this got an error when precompile
> > >long t; //?
> > >EXEC SQL END DECLARE SECTION;
> > >....
> > >EXEC SQL SELECT ((new_time(date,'EST','GMT') -
> > > to_date('01-jan-1970','dd-mon-yyyy'))*24*60*60)
> > > INTO :t
> > > FROM .....
> > >printf("time=%d\n",t);
> > >
> > >but it returns 0 to me...
> > >any advises please!
>

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Share what you know. Learn what you don't. Received on Thu Aug 19 1999 - 22:23:56 CDT