First of all, you need to load DBI.pm into your script for any of the database functions you are using to work. Then you have to connect to the database.

I've got 2 words for you:
perldoc DBI :-)

You really need to read the docs for that(that command will get them for you), and perhaps even give yourself a rundown on packages and modules. Rework your code after that then come back and ask.

For now a little demonstration of DBI.pm:

#!/usr/bin/perl

use DBI;
use strict;

# connect to the database, using mysql in example
my $dbh = DBI->connect("DBI:mysql:dbname:hostname", "user", "pass") or
+ die "Couldn't Connect: $DBI::errstr";

# prepare statement handle
$sth = $dbh->prepare("SELECT * FROM table WHERE field = ?);  
# ? is a placeholder that can be filled when execute is called
$sth->execute($val_of_field) or die "Error: $DBI::errstr";
# $DBI::errstr stores the error string returned by the DB

while (@vals = $sth->fetchrow->array()) {
    # do stuff
    # do more stuff
}
$sth->finish();       #close statement handle
$dbh->disconnect();   #disconnect
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You also need to make sure that DBI.pm is installed on your system. Type:
perl -e 'use DBI;' at your command line. If its installed nothing will happen, if not you'll get an error like:

Can't locate Blah.pm in @INC (@INC contains: /home/harvester/lib/perl5
+/i386-linux /home/harvester/lib/perl5 /usr/lib/perl5/5.00503/i386-lin
+ux /usr/lib/perl5/5.00503 /usr/lib/perl5/site_perl/5.005/i386-linux /
+usr/lib/perl5/site_perl/5.005 .) at -e line 1.
BEGIN failed--compilation aborted at -e line 1.
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Really you should just start out by reading some docs and getting a better understanding of how to use DBI.pm

Amel - f.k.a. - kel