my $query = qq{select distinct dept.deptID, emp.deptID 
    from dept left join emp using(deptID)};

my $sth = $dbh->prepare($query);

$sth->execute();
print "--- names\n";
print join ", ", @{$sth->{NAME}};

print "\n--- fetchrow_hashref\n";
my $row = $sth->fetchrow_hashref();
print "$_ \t" for keys %$row;
print "\n";
$sth->finish();

__OUTPUT__

--- names
deptID, deptID
--- fetchrow_hashref
deptID