#!/usr/bin/perl -wT
use strict;
use POSIX qw(mktime);

my $oct7 = daysago(7,10,2001);

print "October 7th was $oct7 days ago\n";

sub daysago {
  my $day = shift;
  my $month = shift;
  my $year = shift;
  my $then = mktime((localtime)[0..2], $day, $month-1, $year-1900);
  my $delta = time - $then;

  return int($delta/60/60/24);
}

=OUTPUT
October 7th was 24 days ago
[download]

-Blake

select
  mydatefield,
  myvaluestuff
from 
  mytable
where
  mydatefield  between (CURRENT_DATE)-90 and CURRENT_DATE
[download]

Let's attack this slightly differently:

# get date 90 days ago
my ($start_d, $start_m, $start_y)
  = (localtime(time - 90 * 86_400))[3,4,5];

my $start = sprintf('%4d-%02d-%02d', $start_y+1900, 
                                     $start_m+1,
                                     $start_d);

foreach (<FILE>) {
  my ($y, $m, $d) = (split /,/)[28,29,30];

  my $date = sprintf('%4d-%02d-%02d', $y+1900, $m+1, $d);

  if ($start gt $date) {
    # record is more than 90 days old
  } else {
    # record is within 90 days
  }
}
[download]

Update: buckaduck has caught me writing code before drinking coffee. And didn't even point out the worst problems with the code. The new version is (hopefully) better.

Update2: ergh! I give up. This time I was using numeric comparisons instead of string comparisons.

"The first rule of Perl club is you don't talk about Perl club."

His code has changed, and so has the error. Here was my original comment:

What? Am I missing something here? It seems that there are two major flaws in this:

1. I think that the comparison is backwards. If $y >= $start_y then the record is newer (not older) than the date 90 days ago.

2. The date comparison strategy is all wrong. Would Nov. 3 come before Oct. 6, just because 3 <= 6?

Update: And all of this assumes that there are no problems using localtime's month (zero-based) and year (minus 1900) to compare to the records...

About the next version of the code:

Is this method of comparing dates supposed to work in Perl? Not in my version, it doesn't. The dates '2001-10-06' and '2001-11-03' will be EQUAL in a numeric comparison. Numerically, they're both equal to 2001.

And finally...

Yes. This version will do nicely. I made davorg work pretty hard for my ++ this time...

buckaduck

This is along the same lines as another post that has a lot of good discussion on the subject. There are many ways of doing this kind of thing, but I must admit to being a little biased towards my way. :) And if you read through some of the comments you'll see why.

To give a very brief overview, many of the methods deal with converting the number into epoch seconds using timelocal and comparing the dates in epoch seconds using something like $ninetyDaysAgo = time - ($numberOfDays * 86400) and compare $ninetyDaysAgo with the value returned from timelocal.

At any rate, check out that series of posts and you might find some good ideas!

Good luck,
{NULE} --
http://www.nule.org

Positional logic like that is notoriously hard to maintain and debug. (Quick! What is field 14? Which program were you looking at again? What if someone's output is off by one column? What if the spec changes?) If you can, you will save yourself a lot of pain by switching to name based logic, eg by using hashes instead of arrays. True, there is some overhead to doing that, but my experience is that the overhead nothing compared to the savings in development effort.

Hi Tilly,

I agree with your comment, but it's not my database, and that's the only logic that I've come up to parse the information. The database will remain the same though...it's just located in India instead of the US. :-) For the time being, my script is a small part of what the others (that own the DB) will be using it for.

Thanks for all of your suggestions! I really appreciate the quick responses.

-Gus

#!/usr/local/bin/perl5 -wT

print "Content-type: text/html\n\n";

use Date::Calc qw(Delta_Days);

@Months = ('1','2','3','4','5','6','7','8','9','10','11','12'); 
($Month_Day,$Month,$Year) = (localtime)[3,4,5]; 
$Year += 1900;

open(HANDLE,"../script_integration_data/script_integration_records");
while (<HANDLE>) {
   @temp1 = split(/:/);
   $domain = unpack ("A4", $temp1[40]);
   $day_diff = Delta_Days($temp1[28], $temp1[30], $temp1[29], $Year, $
+Month, $Month_Day);
   if (($domain eq "BBA") && ($temp1[36] eq "In Production") && ($day_
+diff <= 90)) { 
      $sum += $temp1[38];
      $count++;
   }
}


close(HANDLE);
$average = $sum / $count;

if ($average >= 44) {
   print sprintf "<blink><font color=\"#FF0000\">%.f days</font></blin
+k>", $average;
   } elsif (($average >= 11) && ($average <= 44)) {
      print sprintf "<font color=\"#FFFF00\">%.f days</font>", $averag
+e;
      } elsif ($average <= 10) {
   print sprintf "<font color=\"#669900\">%.f days</font>", $average;
}


# EOF
[download]