通過Perl腳本從Postgresql數據庫表中選擇不同的輸出

Question

我面臨一個很奇怪的情況。通過perl腳本我連接到Postgresql數據庫，我從具體表中選擇特定的列。來自數據庫的SELECT查詢的輸出被保存到文件中。當腳本第二次執行時，來自第一個選擇的文件內容將被移動到另一個文件，並且實際文件將被填充新的選擇輸出。然後我比較這兩個文件。在執行兩次腳本時它們應該是相同的。問題是，當我運行腳本兩次比較時，它們在一行中不同，當我第三次執行腳本時，輸出與第一次執行時相同，當我執行第四次時，輸出是相同的如同第二次，這些輸出反覆交替。我嘗試了4種不同的方法，如何從表中將選定的行提取到文件中，但仍然是相同的情況，但是，數據庫中表的內容仍然相同。

見下面的代碼：

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"; 
} 

在腳本中，只有一個方法未被註釋和使用的，其餘的都評論。

$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"; 

    }; 

輸出>

# ./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 

你能幫助我嗎？ :) 感謝

問候 哈羅

Answer 1

As Borodin suggested in the comments，我需要print循環後添加

close $out 

。