Question

I’m struggling to figure out how to compare MySQL dates with current system time using perl.

I have a script that runs on a cron job that will send notification if the current system date/time is past the date/time of a returned record:

An application displays a table view:

EventId    Device        Location

CC: 123    something     BFE
TT: 456    anotherthing  BFE

How the script works is it finds values in the field EventID, parses the type (CC:, TT:, etc) from the ID (the numeric portion). The ID is a Unique ID in another database/table which contains an end time field. EventID itself is not Unique and may have duplicate items in the table. Sub routines for each “type” exist since each type has a different database and/or table.

The goal is that the script runs every minute and toggles the value of Expired. It is possible for something to expire, a change to be made and subsequently unexpire.

The script works fine save for 1 issue which appears to be related to timezones based off of the feed back I’ve recieved here so far. If I don’t implicitly set the timezone to ‘America/New_York'($now) for the current system time , it is off by a number of hours ($notz). therefore I need to find a way to make the date returned from MySQL be compared with the current system time accurately.

$now->set_time_zone('America/New_York') does not seem to work either.

I’m unsure of how to do this, or even if the code I have thus far is the best approach (Still fairly new to Perl):

#!/usr/bin/perl
use DBI;
use DateTime;
use DateTime::Format::MySQL;
use Switch;
my $now         = DateTime->now(time_zone => 'America/New_York');
my $notz        = DateTime->now();
my $maindb      = DBI=>connect(database);
my $seteventsql = qq { select * from view where EventId like 'IE:' or EventId like 'TT:' or EventId like 'CC:';};
my $commit      = $livedb->prepare($seteventsql);
$commit->execute() || die "could not set event: $DBI::errstr";

while(@events = $commit->fetchrow_array()) {
                (my $type, my $id) = split (/ /,$events[0]);
                $id =~ s|\D||g;
                switch ($type) {
                        case ('CC:') {check_expired_case($id);}
                        case ('TT:') {check_expired_task($id);}
                        case ('IE:') {check_expired_event($id);}
                }
}

sub check_expired_case {  
        my $id = shift; #id = 123
        my $sql = qq { select id, status_id, item_enddate from item where id = ?; };
        my $exec = $itemdb->prepare($sql);
        $exec->execute($id);
        while(my @row = $exec->fetchrow_array()) {
                my $status = $row[1];
                my $end = DateTime::Format::MySQL->parse_datetime($row[2]);
                if ($now > $end || $status ne 3 || $status ne 6) {
                        $sql = qq { update item set Expired = 1 where EventId = '$eventid';};
                        $maindb->do($sql)
                }else{
                        $sql = qq { update item set Expired = 0 where EventId = '$eventid';};
                        $maindb->do($sql)
                }
        }
        $exec->finish();
}


NoTZ: 2010-09-10T01:27:19 
Now:  2010-09-09T21:27:19
End:  2010-09-10T17:00:00

Thanks in advance. I hope I’ve explained this well enough, its hard difficult to explain how everything relates.

Answer 1

You’ll have to dump the objects to confirm, but it sounds like you have a timezone issue. DateTime::Format::*->parse_datetime (or any other constructor) will use a floating timezone (roughly approximate to UTC) if you don’t specify one, so your comparison will be off by 5 hours.