#!/usr/bin/env perl 
use strict;
use warnings;

my $dql = "20";
my $sql = '20';
my $z   = 20;
my $dqv = "$z";
my $sqv = '$z';

print "dql: $dql\n";
print "sql: $sql\n";
print "dqv: $dqv\n";
print "sqv: $sqv\n";