in reply to Eval not working

Two things,
  1. eval is not failing
  2. An update command that does nothing is not an error so if the condition(id = 1737) is not met nothing happens but no error is thrown.

Update: However the documentation on execute in DBI notes that

For a non-SELECT statement, execute returns the number of rows affected, if known. If no rows were affected, then execute returns "0E0", which Perl will treat as 0 but will regard as true. Note that it is not an error for no rows to be affected by a statement.
Perhaps you could assign the result of $sth->execute() and check to ensure that something was done

print "Good ",qw(night morning afternoon evening)[(localtime)[2]/6]," fellow monks."

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Re^2: Eval not working
by DooDah (Novice) on Sep 03, 2010 at 11:11 UTC
    Thanks Utilitarian for explaining that.

    Am I right in saying the only way to catch a problem like that would be to use the 'affected rows' function?
[reply]
        $dbh->{AutoCommit} = 0; 
  $dbh->{RaiseError} = 1;

  my $id = 737;

  my $rows;
  if (!eval {
      my $sql = "UPDATE stockhistory SET invoiced = 1 WHERE id = ?";
      my $sth = $dbh->prepare($sql);
      $rows = $sth->execute($id);
      $dbh->commit();
      1
  }) {
      print "Transaction aborted because $@";
      $dbh->rollback();
  }

  die("Record $id not found") if $rows < 1;

      [download]

      Note: Can't check if $rows is true since "0E0" (equal to zero but true) is returned when no rows are affected.

[reply]
[d/l]
        Thanks for all your help monks.
        I'll re-write my script to include your suggestions.
[reply]

      Exactly.

      Your query might successfully update every record in the table, or only one, or none at all, but it ran successfully. The number of rows affected is provided by: 

      print 'The query updated '. $sth->rows . " rows.\n";

      [download]

      As Occam said: Entia non sunt multiplicanda praeter necessitatem.

[reply]
[d/l]

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