sub update {
  my $stmt = "UPDATE tabellenname SET spalte1 = ?, spalte2 = ? WHERE spalte3 = ?";
  my $rows = $dbh->do( $stmt, undef, @_[0..2] );

  print "$rows Zeilen aktualisiert\n";

  $dbh->commit;
}

update($spalte1, $spalte2, $spalte3);