use strict;
use DBI;

my $dbh = DBI->connect(
   "DBI:CSV:f_dir=.;csv_eol=\n;csv_sep_char= ;",
   {RaiseError=>1},
);

$dbh->{csv_tables}->{'users'} = { 
   file      => 'users.csv',
   col_names => [qw(id email user passwd)],
};

my $user = shift;
my $pass = shift;

my $sth = $dbh->prepare("
   select id,email,user,passwd 
   from users
   where user = ?
   and passwd = ?
");
$sth->execute($user,$pass);

my $valid = $sth->fetchrow_hashref;
die "bad user/pass" unless $valid;

my $id    = $valid->{id};
my $email = $valid->{email};