#!perl
use strict;
use warnings;
sub foo {
warn "wantarray() in foo() is: ", wantarray(), "\n";
my @r = 3 .. 8;
return @r;
}
my @x = foo() or warn "in ... or warn() #1\n";
warn "[EMAIL PROTECTED]: @x\n";
my $x = foo() or warn "in ... or warn() #2\n";
warn "\$x: $x\n";
> -----Original Message-----
> From: Michael Stassen [mailto:[EMAIL PROTECTED]
> Sent: Tuesday, June 21, 2005 12:48 PM
> To: olly@lfix.co.uk
> Cc: debian-user@lists.debian.org; mysql@lists.mysql.com
> Subject: Re: Sarge problems with MySQL and DBI / DBD::mysql
>
> Oliver Elphick wrote:
>
> > We have an application that has just upgraded to Debian
> sarge with mysql
> > upgrading from 3.23.49 to 4.0.24. As far as I know I have
> followed all
> > the procedures for upgrading the database.
> >
> > Some queries always fail in DBD::mysql (in DBI) although
> they work OK
> > with the mysql client.
> >
> > For example, this SQL command:
> >
> > SELECT description
> > FROM IncoCountry
> > WHERE value = "EW";
> >
> > which returns 0 rows, works correctly in mysql. But when
> it is passed
> > through this statement in Perl:
> >
> > my @row = $dbh->selectrow_array($sql) or
> > &failed(__FILE__, __LINE__,
> > "Failed to run the sql statement with error
> > $DBI::errstr");
> >
> > it fails inside DBD::mysql without giving any message in
> $DBI::errstr:
>
> This does not fail. Your logic is wrong. You are evaluating
> $dbh->selectrow_array($sql) in a scalar context
> (selectrow_array or ...).
> According to `perldoc DBI`, in the section on
> selectrow_array, "in a scalar
> context, an "undef" is returned if there are no more rows".
> Your query
> successfully returns 0 rows, so $dbh->selectrow_array($sql)
> is "undef". undef
> is false, so the part of your query after the "or" gets run.
> You've coded an
> error message which claims the query produced a DBI error,
> but it did not.
>
> > DBD::mysql::db::prepare(/usr/lib/perl5/DBD/mysql.pm:208):
> > 208: my $sth = DBI::_new_sth($dbh, {'Statement' =>
> $statement});
> > DB<2> n
> > DBD::mysql::db::prepare(/usr/lib/perl5/DBD/mysql.pm:211):
> > 211: if (!DBD::mysql::st::_prepare($sth, $statement,
> $attribs)) {
> > DB<2> s
> > DBD::mysql::db::prepare(/usr/lib/perl5/DBD/mysql.pm:215):
> > 215: $sth;
> > DB<2> s
> >
> main::failed(/home/domain/www.chpresenters.co.uk/web/cgi-bin/o
> cms-multi/common/cgi-lib.pl:117):
> >
> > If a row is added to the table to be returned by this
> query, the problem
> > goes away.
> >
> > How can I debug or fix this problem, please?
>
> You need to revise your code to distinguish between DBI
> errors and 0 rows
> returned.
>
> Michael
>
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