I have read through the DBI docs and DBD::mysql docs a couple times and
think I have a grasp of this whole deal but thought I would see what the
gurus have to say on the matter. For reference I am at Perl 5.8.1, DBI
1.38, DBD::mysql 2.9002, mysql 3.23.56. I normally handle my own errors
rather than using RaiseError and have AutoCommit set to the default. To
prevent having to rewrite a bunch of other code at the moment my goal is
to leave it that way and "just do the right thing" where I need
transaction support. My code model (pseudo) at this point looks like:
$dbh holds an already initialized database handle
# localize the setting of dbh handle attributes
{
local $dbh->{AutoCommit} = 0;
local $dbh->{RaiseError} = 1;
# now perform our steps inside of an eval, allowing us to catch the
# exceptions triggering a rollback
my $sth;
eval {
my $st = "SELECT * ....";
my @bind = ( bind values );
$sth = $dbh->prepare($st);
$sth->execute(@bind);
$dbh->commit;
}
if ($@) {
$dbh->rollback;
# throw my normal exception stuffs here
}
}
Questions:
1) Can/should I do the 'local' setting of the attributes within the eval
block without causing any other issues? I can't think of reasons not
to, but maybe you can?
2) If the answer to number 1 is no, then presumably 'rollback' throws an
exception itself so I would have to catch it too with an 'eval'? Can
rollback fail? If I can move the settings inside of the 'eval' then
rollback failing should do "normal" error reporting correct, is that
returning undef or true?
3) Similar to #2, setting AutoCommit to 0 before setting the RaiseError
would mean I need to check that it succeeds (which is just checking the
boolean context of the attribute) moving it into the eval should mean I
can put it after the RaiseError and let the eval catch its exception as
well, correct?
Just trying to get this whole thing clear, thanks for your time,
http://danconia.org
