Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks!
I am working on a program and I have to calculate if the date (stored) coming from the database is older than today's date. I have this sample code that works, my question is if this is an efficient way of doing this, here the code I have:
#!/usr/bin/perl

use strict;
use CGI;
use CGI::Carp qw/fatalsToBrowser warningsToBrowser/;
use Date::Calc qw(Delta_Days);
use Date::Calc qw[Add_Delta_Days Today];

my $q = new CGI;

print $q->header;

my $got_date = "1/1/2010"; # this is only to show, but this is the for
+mat of the date I will be getting from the db table.
my ($got_month,$got_day,$got_year) = split /\//, $got_date; # split da
+te in 3 parts with / as delimiter

my ($year, $month, $day) = Today();

my @today = ($year, $month, $day);
my @date_got  = ($got_year, $got_month, $got_day);

my $difference = Delta_Days(@date_got, @today);

print "There were $difference days between Today and Stored Date\n\n";

[download]


Thanks for the Help!

Replies are listed 'Best First'.
Re: Subtracting certain number of days from current date.
by stefbv (Priest) on Feb 03, 2010 at 20:17 UTC

    I don't know about the efficiency but here is how i would write it, (ignoring the CGI part).

    use strict;
use warnings;

use Date::Calc qw(Delta_Days Decode_Date_US Today);

my $date1 = '1/1/2010'; # Supose date is in US format

my ( $year , $month , $day  ) = Today();
my ( $year1, $month1, $day1 ) = Decode_Date_US($date1);

my $dd = Delta_Days( $year1, $month1, $day1, $year, $month, $day );

print "There were $dd days between Today and $date1\n";

    [download]
[reply]
[d/l]
      Unless you have a later use for the parts of the dates, why not: 
      my $dd = Delta_Days( Decode_Date_US($date1), Today() );

      [download]
[reply]
[d/l]
Re: Subtracting certain number of days from current date.
by ahmad (Hermit) on Feb 04, 2010 at 00:12 UTC

    If you are working in database then you could use some kind of built-in function in your query (few people said it would be faster) -- never done the benchmarking myself.

    For example in mysql you can do it this way.

    SELECT *,DATEDIFF(NOW(),`YourDateField`) AS `DiffDate` FROM `table` WH
+ERE `x` = 'y'

this will return an additional column for every row containing the dat
+e difference between the current date and the date stored in the data
+base.

    [download]
[reply]
[d/l]
Re: Subtracting certain number of days from current date.
by ikegami (Patriarch) on Feb 03, 2010 at 20:03 UTC
    Do you have any reason to think it's not efficient?
[reply]
      Maybe how the "split" is in the date coming from the DB? What if the format of the date changes?
[reply]

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