On Tue, Nov 19, 2002 at 05:57:56PM -0500, Jeff Urlwin wrote:
> > code snippet:
> >
> > use DBI;
> > my $dbh = DBI->connect('DBI:ODBC:OST', 'user', 'pass')
> > or die "Couldn't connect to database: " . DBI->errstr;
> >
> > sub get_max_id {
> > my $be_table=@_[0];
> > my $st_maxid = $dbh->prepare("select max(OST_ID) from $be_table where
> > event_status='U'");
> > $st_maxid->execute();
> > my $maxid = $st_maxid->fetchrow_array;
> > $st_maxid->finish;
>
> You're getting an array back from fetchrow_array, not a scalar.
>
> my @row = $st_maxid->fetchrow_array;
> my $maxid = defined(@row) ? $row[0] : undef;
>
> The above should work
Umm, defined() shouldn't be used on arrays - it doesn't mean what you expect.
This would be okay:
my $maxid = @row ? $row[0] : undef;
but since $row[0] would be undef anyway if there are no elements in @row
you could just write
my $maxid = $row[0];
And since there's only one field being selected fetchrow_array will
return that field when called in a scalar context, so you could just
write:
my $maxid = $st_maxid->fetchrow_array;
But since the prepare+execute+fetch+finish are all in sequence you
could replace them all with:
my $maxid = $dbh->selectrow_array(qq{
SELECT max(OST_ID) FROM $be_table WHERE event_status='U'
});
and, if you want to map undef (due to no rows matching) to something else,
I'd do this:
$maxid = 0 unless defined $maxid;
It's important to remember that if you're _not_ using RaiseError then undef
can be returned due to an error. So when no using RaiseError you should always
add a test for "if ($DBI::err) { ... }".
Tim.
