通过Perl脚本从Postgresql数据库表中选择不同的输出

Question

我面临一个很奇怪的情况。通过perl脚本我连接到Postgresql数据库，我从具体表中选择特定的列。来自数据库的SELECT查询的输出被保存到文件中。当脚本第二次执行时，来自第一个选择的文件内容将被移动到另一个文件，并且实际文件将被填充新的选择输出。然后我比较这两个文件。在执行两次脚本时它们应该是相同的。问题是，当我运行脚本两次比较时，它们在一行中不同，当我第三次执行脚本时，输出与第一次执行时相同，当我执行第四次时，输出是相同的如同第二次，这些输出反复交替。我尝试了4种不同的方法，如何从表中将选定的行提取到文件中，但仍然是相同的情况，但是，数据库中表的内容仍然相同。

见下面的代码：

use strict; 
use warnings; 
use DBI; 
use DBD::Pg; 
use File::Copy; 
use File::Compare; 
use List::Compare; 
use MIME::Lite; 
use Data::Dumper; 
use Sys::Hostname; 

my $qry1 = "select id, name from nms_incident_config where enable = 'f' order by name asc"; 
my $ltraps = '/tmp/traps.list' ; 
my $ntraps = '/opt/tools/trapcfg_check/actual_traps.list'; 

if(-e $ntraps) { 
    print "Actual trap list exists \n"; 
    move("$ntraps","$ltraps") or die "Copy failed! :$!"; 
     }; 

open my $out ,">", "/opt/tools/trapcfg_check/actual_traps.list"; 

#connect to db and run selects for further use 

my $db = DBI->connect("dbi:Pg:dbname=<db_name>;host=localhost;","postgres", "*******", {'RaiseError' => 1}); 

my $qry1s = $db-> prepare("$qry1"); 
$qry1s->execute(); 

方法1

while (my @row = $qry1s -> fetchrow_array()) { 
    $" = ","; 
    print $out "@row \n"; 
    } 

方法2

while (my @row = $qry1s->fetchrow_array()) { 
    #print $out "$row[0],$row[1]\n"; 
    print $out join(", ", @row), "\n" 
} 

方法3

my ($id,$name); 
$qry1s->bind_columns(\($id, $name)); 
while ($qry1s->fetch){ 
    print $out "$id, $name\n" 
} 

方法4

my $row; 
$row = $qry1s->fetchall_arrayref([]); 
foreach my $r (@{$row}) 
{ 
    print $out join(", ", @{$r}), "\n"; 
} 

在脚本中，只有一个方法未被注释和使用的，其余的都评论。

$db->disconnect(); 

open F ,"</opt/tools/trapcfg_check/actual_traps.list" or die $!; 
open F1 , "/tmp/traps.list" or die $!; 

my @ntraps=<F>; 
my @ltraps=<F1>; 

my @lonly ; 
my @nonly ; 

    if (compare($ltraps,$ntraps) == 0) { 
     print "Files are same \n" ; 
     die "Files are same\n"; 
     }; 

    if (compare($ltraps,$ntraps) ne 0) { print "Files are different\n"; 

     my $tc = List::Compare->new(\@ltraps, \@ntraps); 
     @lonly = $tc->get_complement; 
#  @nonly = $tc->get_unique; 
     print "Different row/s in new trap list: "."@lonly\n"; 

    }; 

输出>

# ./tcheck_2.pl 
Actual trap list exists 

Files are same 
Files are same 

# cat /opt/tools/trapcfg_check/actual_traps.list | grep -i 2147590214 
2147590214, wlsxStaUnAssociatedFromUnsecureAP 

# cat /tmp/traps.list | grep -i 2147590214 
2147590214, wlsxStaUnAssociatedFromUnsecur 

# ./tcheck_2.pl 
Actual trap list exists 

Files are different 
Different row/s in new trap list: 2147590214, wlsxStaUnAssociatedFromUnsecur 

# cat /opt/tools/trapcfg_check/actual_traps.list | grep -i 2147590214 
2147590214, wlsxStaUnAssociatedFromUnsecur 

# cat /tmp/traps.list | grep -i 2147590214 
2147590214, wlsxStaUnAssociatedFromUnsecureAP 

# ./tcheck_2.pl 
Actual trap list exists 

Files are same 
Files are same 

# cat /opt/tools/trapcfg_check/actual_traps.list | grep -i 2147590214 
2147590214, wlsxStaUnAssociatedFromUnsecureAP 

# cat /tmp/traps.list | grep -i 2147590214 
2147590214, wlsxStaUnAssociatedFromUnsecur 

# ./tcheck_2.pl 
Actual trap list exists 

Files are different 
Different row/s in new trap list: 2147590214, wlsxStaUnAssociatedFromUnsecur 

# cat /opt/tools/trapcfg_check/actual_traps.list | grep -i 2147590214 
2147590214, wlsxStaUnAssociatedFromUnsecur 

# cat /tmp/traps.list | grep -i 2147590214 
2147590214, wlsxStaUnAssociatedFromUnsecureAP 

你能帮助我吗？ :) 感谢

问候 哈罗

Answer 1

As Borodin suggested in the comments，我需要print循环后添加

close $out 

。