Most posts in this thread concentrate on how to catch the error message, but I don't think that's the real issue. wog's message touches on it. The eval should put the database handle somewhere so that a cleanup routine can deal with it in case there's an error. You might try something like this:

eval {
  my $dbh = DBI->connect(..., {RaiseError=>1});
  eval {
    $dbh->do("update ...");
    $dbh->do("update ...");
  };
  if ($@) {
    # clean up after an unsuccessful update
    $dbh->rollback();
    $dbh->disconnect();
    die($@);  # reraise the error
  }
  # successful update
  $dbh->commit();
  $dbh->disconnect();
};
if ($@) {
  log($@);
}
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