my $csv = qq{foo,,bar,''};

##</code><code>##

#!/usr/bin/perl -w

use DBI;
use strict;

my $db = DBI->connect("DBI:CSV:f_dir=/home/arturo/testing")
        or die "Cannot connect: $DBI::errstr\n";

=pod

# used to create the table
my $sth = $db->prepare("CREATE TABLE foo (id  INTEGER,
                                          firstname VARCHAR(32),
                                          lastname      VARCHAR(32) )");

$sth->execute;

$sth = $db->prepare("INSERT INTO foo (id, firstname, lastname) VALUES (?,?,?)");
$sth->execute(1, 'Charo', '');
$sth->execute(2, 'Wynonna', undef);
$sth->execute(3, undef, 'Cher');
$sth->execute(4, '', "Sting");

# note: Charo has a blank last name, Wynonna has an undef one
# Cher has undef first name, Sting has blank first name

=cut

my $sth = $db->prepare("SELECT id, firstname, lastname FROM foo") 
	or die "Cannot prepare: $DBI::errstr\n";

# next line currently causes an error on my system 
# (fresh installs of all the modules on which DBD::CSV depends)

# UPDATE the answer, of course, is to execute it first 
# /me LARTs himself

$sth->execute();

while ( my ($id, $first, $last) = $sth->fetchrow_array() ) {
        print "First name '$first' is " .
                ($first eq '' && defined $first) ? "blank" : "undefined";
        print "Second name '$last' is " .
                ($last eq '' && defined $last ) ? "blank" : "undefined";
}

$db->disconnect;