perl fetchrow_array 只返回最后一列而不是所有列答案

【问题标题】：perl fetchrow_array returning only the last column instead of all of the columnsperl fetchrow_array 只返回最后一列而不是所有列
【发布时间】：2017-01-24 23:57:00
【问题描述】：

我正在编写一个名为“hlstats.pl”的脚本，它是来自 http://www.hlstats-community.org/ 的《半条命》游戏的统计服务器

我正在尝试在带有 MySQL 的 Windows 上的 Strawberry perl 上运行它。

我已将问题隔离为 fetchrow_array 仅返回查询中最后一列的内容。
这是我从 hlstats.pl 修改的代码 sn-p

# load the options from DB
my $result = &doQuery("SELECT keyname, value FROM `${db_prefix}_Options`");
my @row;
while (@row = $result->fetchrow_array()) {
  foreach $field (@row) {
    if (defined($field)) {
      print "$field\n";
    } else {    
      print "<NULL>\n";
    }
  }
} 
##my ($keyname, $value, %oHash);
##while( ($keyname, $value) = $result->fetchrow_array ) {
##  # $oHash{$keyname} = $value;
##  print $keyname;
##  print "\n";
##}
$result->finish();

如果它是最后一个，它将打印出“值”列中的所有值，我可以反转它，它将打印所有如果我在查询中移动这些值，则“键名”列中的值。我不清楚为什么我们没有收到所有的专栏。

这是为 MSWin32-x86-multi-thread 构建的 perl v5.10.0

MySQL 版本 5.7.10

“perldoc perllocal”输出

  Thu Jan 29 21:17:27 2009: "Module" ExtUtils::MakeMaker
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 6.48"

    *   "EXE_FILES: bin/instmodsh"

  Thu Jan 29 21:17:32 2009: "Module" File::Path
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.07"

    *   "EXE_FILES: "

  Thu Jan 29 21:17:38 2009: "Module" ExtUtils::Command
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.16"

    *   "EXE_FILES: "

  Thu Jan 29 21:17:47 2009: "Module" Win32API::File
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.1101"

    *   "EXE_FILES: "

  Thu Jan 29 21:18:05 2009: "Module" ExtUtils::Install
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.52"

    *   "EXE_FILES: "

  Thu Jan 29 21:18:10 2009: "Module" ExtUtils::Manifest
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.56"

    *   "EXE_FILES: "

  Thu Jan 29 21:18:34 2009: "Module" Test::Harness
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 3.14"

    *   "EXE_FILES: bin/prove"

  Thu Jan 29 21:18:43 2009: "Module" Test::Simple
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.86"

    *   "EXE_FILES: "

  Thu Jan 29 21:18:48 2009: "Module" ExtUtils::CBuilder
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.24"

    *   "EXE_FILES: "

  Thu Jan 29 21:18:54 2009: "Module" ExtUtils::ParseXS
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.19"

    *   "EXE_FILES: "

  Thu Jan 29 21:19:05 2009: "Module" version
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.76"

    *   "EXE_FILES: "

  Thu Jan 29 21:19:11 2009: "Module" IO::Compress::Base
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.015"

    *   "EXE_FILES: "

  Thu Jan 29 21:19:23 2009: "Module" Compress::Raw::Zlib
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.015"

    *   "EXE_FILES: "

  Thu Jan 29 21:19:33 2009: "Module" Compress::Raw::Bzip2
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.015"

    *   "EXE_FILES: "

  Thu Jan 29 21:20:34 2009: "Module" IO::Compress::Zlib
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.015"

    *   "EXE_FILES: "

  Thu Jan 29 21:20:47 2009: "Module" IO::Compress::Bzip2
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.015"

    *   "EXE_FILES: "

  Thu Jan 29 21:20:55 2009: "Module" Compress::Zlib
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.015"

    *   "EXE_FILES: "

  Thu Jan 29 21:21:18 2009: "Module" Compress::Bzip2
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.09"

    *   "EXE_FILES: "

  Thu Jan 29 21:21:24 2009: "Module" IO::Zlib
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.09"

    *   "EXE_FILES: "

  Thu Jan 29 21:21:31 2009: "Module" Cwd
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 3.29"

    *   "EXE_FILES: "

  Thu Jan 29 21:21:53 2009: "Module" File::Temp
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.21"

    *   "EXE_FILES: "

  Thu Jan 29 21:22:03 2009: "Module" Win32::WinError
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.03"

    *   "EXE_FILES: "

  Thu Jan 29 21:22:14 2009: "Module" Win32API::Registry
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.30"

    *   "EXE_FILES: "

  Thu Jan 29 21:22:19 2009: "Module" Win32::TieRegistry
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.25"

    *   "EXE_FILES: "

  Thu Jan 29 21:22:24 2009: "Module" File::HomeDir
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.82"

    *   "EXE_FILES: "

  Thu Jan 29 21:22:29 2009: "Module" File::Which
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.05"

    *   "EXE_FILES: bin/pwhich"

  Thu Jan 29 21:22:42 2009: "Module" Archive::Zip
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.26"

    *   "EXE_FILES: bin/crc32"

  Thu Jan 29 21:22:46 2009: "Module" Package::Constants
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.02"

    *   "EXE_FILES: "

  Thu Jan 29 21:22:51 2009: "Module" IO::String
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.08"

    *   "EXE_FILES: "

  Thu Jan 29 21:22:59 2009: "Module" Archive::Tar
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.44"

    *   "EXE_FILES: bin/ptar bin/ptardiff"

  Thu Jan 29 21:23:04 2009: "Module" Parse::CPAN::Meta
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.04"

    *   "EXE_FILES: "

  Thu Jan 29 21:23:16 2009: "Module" YAML
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.68"

    *   "EXE_FILES: "

  Thu Jan 29 21:23:23 2009: "Module" Digest::MD5
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.38"

    *   "EXE_FILES: "

  Thu Jan 29 21:23:29 2009: "Module" Digest::SHA1
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.11"

    *   "EXE_FILES: "

  Thu Jan 29 21:23:38 2009: "Module" Digest::SHA
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 5.47"

    *   "EXE_FILES: shasum"

  Thu Jan 29 21:25:58 2009: "Module" CPAN
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.9301"

    *   "EXE_FILES: scripts/cpan"

  Thu Jan 29 21:26:05 2009: "Module" Term::ReadKey
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.30"

    *   "EXE_FILES: "

  Thu Jan 29 21:26:09 2009: "Module" Term::ReadLine
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.0302"

    *   "EXE_FILES: "

  Thu Jan 29 21:26:13 2009: "Module" Text::Glob
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.08"

    *   "EXE_FILES: "

  Thu Jan 29 21:26:24 2009: "Module" URI
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.37"

    *   "EXE_FILES: "

  Thu Jan 29 21:26:28 2009: "Module" HTML::Tagset
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 3.20"

    *   "EXE_FILES: "

  Thu Jan 29 21:26:41 2009: "Module" HTML::Parser
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 3.59"

    *   "EXE_FILES: "

  Thu Jan 29 21:27:18 2009: "Module" LWP
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 5.823"

    *   "EXE_FILES: bin/lwp-request bin/lwp-mirror bin/lwp-rget
        bin/lwp-download"

  Thu Jan 29 21:27:31 2009: "Module" LWP::Online
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.07"

    *   "EXE_FILES: "

  Thu Jan 29 21:27:56 2009: "Module" Win32::File
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.06"

    *   "EXE_FILES: "

  Thu Jan 29 21:28:17 2009: "Module" File::Remove
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.42"

    *   "EXE_FILES: "

  Thu Jan 29 21:28:21 2009: "Module" Win32::File::Object
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.01"

    *   "EXE_FILES: "

  Thu Jan 29 21:28:45 2009: "Module" Win32::API
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.58"

    *   "EXE_FILES: "

  Thu Jan 29 21:29:05 2009: "Module" Params::Util
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.35"

    *   "EXE_FILES: "

  Thu Jan 29 21:29:14 2009: "Module" IPC::Run3
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.042"

    *   "EXE_FILES: "

  Thu Jan 29 21:29:19 2009: "Module" Test::Script
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.03"

    *   "EXE_FILES: "

  Thu Jan 29 21:29:24 2009: "Module" Win32::Env::Path
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.01"

    *   "EXE_FILES: script/win32envpath"

  Thu Jan 29 21:29:46 2009: "Module" Parse::Binary
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.11"

    *   "EXE_FILES: "

  Thu Jan 29 21:29:51 2009: "Module" Win32::Exe
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.11"

    *   "EXE_FILES: script/exe_update.pl"

  Thu Jan 29 21:30:32 2009: "Module" Math::BigInt
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.89"

    *   "EXE_FILES: "

  Thu Jan 29 21:30:52 2009: "Module" Math::BigInt::FastCalc
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.19"

    *   "EXE_FILES: "

  Thu Jan 29 21:31:14 2009: "Module" Math::BigRat
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.22"

    *   "EXE_FILES: "

  Thu Jan 29 21:31:37 2009: "Module" Math::BigInt::GMP
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.24"

    *   "EXE_FILES: "

  Thu Jan 29 21:31:49 2009: "Module" XML::Parser
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.36"

    *   "EXE_FILES: "

  Thu Jan 29 21:32:18 2009: "Module" XML::NamespaceSupport
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.09"

    *   "EXE_FILES: "

  Thu Jan 29 21:32:28 2009: "Module" XML::SAX
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.96"

    *   "EXE_FILES: "

  Thu Jan 29 21:32:41 2009: "Module" XML::LibXML::Common
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.13"

    *   "EXE_FILES: "

  Thu Jan 29 21:33:01 2009: "Module" XML::LibXML
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.69"

    *   "EXE_FILES: "

  Thu Jan 29 21:33:30 2009: "Module" PAR::Dist
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.43"

    *   "EXE_FILES: "

  Thu Jan 29 21:33:37 2009: "Module" PAR::Dist::FromPPD
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.03"

    *   "EXE_FILES: bin/ppd2par"

  Thu Jan 29 21:33:42 2009: "Module" PAR::Dist::InstallPPD
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.02"

    *   "EXE_FILES: bin/parinstallppd"

  Thu Jan 29 21:34:18 2009: "Module" IO::Stringy
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.110"

    *   "EXE_FILES: "

  Thu Jan 29 21:34:41 2009: "Module" Tree::DAG_Node
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.06"

    *   "EXE_FILES: "

  Thu Jan 29 21:35:03 2009: "Module" Test::Warn
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.11"

    *   "EXE_FILES: "

  Thu Jan 29 21:35:21 2009: "Module" Test::Tester
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.107"

    *   "EXE_FILES: "

  Thu Jan 29 21:35:27 2009: "Module" Test::NoWarnings
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.084"

    *   "EXE_FILES: "

  Thu Jan 29 21:35:34 2009: "Module" Test::Deep
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.103"

    *   "EXE_FILES: "

  Thu Jan 29 21:35:39 2009: "Module" DBM::Deep
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.0013"

    *   "EXE_FILES: "

  Thu Jan 29 21:35:59 2009: "Module" YAML::Tiny
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.36"

    *   "EXE_FILES: "

  Thu Jan 29 21:36:23 2009: "Module" AutoLoader
*       "installed into: C:\strawberry\perl\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 5.68"

    *   "EXE_FILES: "

  Thu Jan 29 21:36:29 2009: "Module" PAR
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.984"

    *   "EXE_FILES: "

  Thu Jan 29 21:36:34 2009: "Module" PAR::Repository::Query
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.12"

    *   "EXE_FILES: "

  Thu Jan 29 21:36:39 2009: "Module" PAR::Repository::Client
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.21"

    *   "EXE_FILES: "

  Thu Jan 29 21:36:49 2009: "Module" PPM
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.01_01"

    *   "EXE_FILES: bin/ppm.pl"

  Thu Jan 29 21:37:09 2009: "Module" Number::Compare
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.01"

    *   "EXE_FILES: "

  Thu Jan 29 21:37:19 2009: "Module" pler
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.34"

    *   "EXE_FILES: script/pler"

  Thu Jan 29 21:37:44 2009: "Module" Data::Compare
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.21"

    *   "EXE_FILES: "

  Thu Jan 29 21:37:50 2009: "Module" CPAN::Checksums
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 2.02"

    *   "EXE_FILES: "

  Thu Jan 29 21:37:56 2009: "Module" File::chmod
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.32"

    *   "EXE_FILES: "

  Thu Jan 29 21:38:01 2009: "Module" CPAN::Inject
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.11"

    *   "EXE_FILES: script/cpaninject"

  Thu Jan 29 21:38:15 2009: "Module" pip
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.13"

    *   "EXE_FILES: script/pip"

  Thu Jan 29 21:39:33 2009: "Module" DBI
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.607"

    *   "EXE_FILES: dbiproxy dbiprof dbilogstrip"

  Thu Jan 29 21:40:00 2009: "Module" DBD::SQLite
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 1.14"

    *   "EXE_FILES: "

  Thu Jan 29 21:40:20 2009: "Module" CPAN::DistnameInfo
*       "installed into: C:\strawberry\perl\site\lib"

    *   "LINKTYPE: dynamic"

    *   "VERSION: 0.07"

    *   "EXE_FILES: "

use strict;
use warnings;

use DBI;

print map "$_\n",
      DBI->available_drivers;

输出是：

数据库管理
示例P
文件
Gofer
多路复用
代理
SQLite
海绵
mysql

【问题讨论】：

您能否尝试将SELECT 查询更改为：SELECT 111 AS keyname, 222 AS value 以查看它是否会出现相同的问题。之后，您也可以提供一个显示问题的独立程序，因为不会引用您的实际表格。
您在问题中说提供的代码是从原始程序“修改”的。仔细检查一下，在实际程序中，你确实有@row = $result->fetchrow_array。你描述的问题听起来像是如果你不小心写了$row = $result->fetchrow_array会发生什么。
请原谅我正在为 Perl 苦苦挣扎。谢天谢地，已经有 stackoverflow 了！我的理解是@row 是一个数组，因为它是用@ 而不是$ 定义的。那么语句不会：@row = $result->fetchrow_array() 将数组结果赋值给数组变量？
@tjd, fetchrow_array 在列表上下文中被调用
Re "这是我从 hlstats.pl 修改的代码 sn-p"，不好。向我们提供实际显示问题的代码。

标签： mysql perl dbi

【解决方案1】：

你的真实代码很可能有这个

while ( $row = $result->fetchrow_array() ) {

    foreach $field ( $row ) {

        if ( defined($field) ) {
            print "$field\n";
        }
        else {    
            print "<NULL>\n";
        }
    }
}

documentation for fetchrow_array 这么说

如果在标量上下文中为多列的语句句柄调用，则未定义驱动程序将返回第一列的值还是最后一列的值。所以不要那样做。

我会写这个

while ( my @row = $result->fetchrow_array ) {
    print "$_\n" for map { $_ // '<NULL>' } @row;
}

或者你可以像这样使用fetchrow_arrayref

while ( my $row = $result->fetchrow_arrayref ) {
    print "$_\n" for map { $_ // '<NULL>' } @$row;
}

当我们看不到您看到的内容时，很难发现错误。请注意显示真实的源代码，或者您已经测试并产生相同症状的东西。

【讨论】：