#!/usr/bin/env perl

use strict;
use warnings;
use Data::Dumper;

my $driver  = "Pg"; 
my $database = "dbase";
my $dsn = "DBI:$driver:dbname = $database;host = 127.0.0.1;port = 5432
+";
my $userid = "postgres";
my $password = "postgres";
my $dbh = DBI->connect($dsn, $userid, $password, { RaiseError => 1, Au
+toCommit => 0 }) 
   or die $DBI::errstr;

print "Opened database successfully\n";

my $selsth = $dbh->prepare("SELECT * FROM logs_column WHERE logged_in 
+> NOW()::timestamp - interval '24 hours'")
    or die($dbh->errstr);

if(!$selsth->execute) {
    die($dbh->errstr);
}

my @lines;
while((my $line = $selsth->fetchrow_hashref)) {
    # push hashref of each row into @lines
    push @lines, $line;
}
$dbh->commit;

# To check if this is the structure you want:
print Dumper(\@lines);

$dbh->disconnect;

...

open(my $ofh, '>', 'bla.log') or die($!);
foreach my $line (@lines) {
    print $ofh join(';', $line->{timestamp}, $line->{logtext}), "\n";
}
close $ofh;
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Something like that?