my $result_rows = $sth->fetchall_arrayref;

if ( ref( $result_rows ne 'ARRAY' or @$result_rows == 0 ) {
    print "Oops! No data.  Now what?\n";
}
else {
    print "Yo! you got " . scalar( @$result_rows ) . " records:\n";
    for my $row ( @$result_rows ) {
        print join( "\t", @$row ), "\n";
    }
}