##
use Plack::Request;
use DBI;
use Conf;
use Modern::Perl;
my $env = shift;
my $qd = $req->parameters->mixed;
my $dbh = DBI->connect(
$Conf::conf->{'dsn'},
$Conf::conf->{'dsn_username'},
$Conf::conf->{'dsn_password'}
) || die "Could not connect to
database: $DBI::errstr";
my $sth = $dbh->prepare(qq@
SELECT count(1) FROM users
WHERE username="$qd->{'username'}"
@);
$sth->execute;
....
....