use DBI;

. . .

my $res = $sth->fetchall_arrayref(); # Returns array ref with all result rows which are array refs too.
for my $row (@$res) {
    for my $value (@$row) { print "$value " }
    print "\n";
}

##</code><code>##

my $res = $sth->fetchall_arrayref({}); # Returns array ref with result rows which are hash refs.

for my $row (@$res) {
    for my $key (%$row) { print "$$row{$key} " }
    print "\n"; 
}