use DBI;
use strict;

# Variable für SQL Befehle
my $sql;

# DB Parameter
my ($db_user, $db_name, $db_pass, $db_host) = ('root', 'observium', 'lunakoshix', 'localhost');

# DB connect
my $dbh = DBI->connect("DBI:mysql:database=$db_name;host=$db_host", $db_user, $db_pass) or die "Cannot connect to DB\n";

$sql = "select distinct ifname from ports 
inner join devices on ports.device_id = devices.device_id
where devices.type = 'network'
order by ifname asc";

my $rows = $dbh->selectall_arrayref("$sql");
foreach (@$rows) {
   # für jeden Eintrag
   my $row=$_;
   my $ifname=$row->[0];
   print "$ifname\n";
}

$sql = "select hostname from devices
where devices.type = 'network'
order by hostname asc";

my $rows = $dbh->selectall_arrayref("$sql");
foreach (@$rows) {
   # für jeden Eintrag
   my $row=$_;
   my $hostname=$row->[0];
   print "$hostname\n";
}