#!perl
use strict;
use warnings;
use DBI;
my $localDB = _dbh();

# build list of ids
my $sql1 = << 'SQL1';
  SELECT ID FROM A_TEMP2
SQL1
my $sth1 = $localDB->prepare($sql1);
$sth1->execute();
my $records = $sth1->fetchall_arrayref();
$sth1->finish;

# build list of dblinks
my $sql2 = << 'SQL2';
  SELECT DBLINK FROM A_TEMP3
  WHERE ID = ?
SQL2
my $sth2 = $localDB->prepare($sql2);

for (@$records){
  my $id = $_->[0];
  $sth2->execute($id);
  while ( (my $dblink) = $sth2->fetchrow_array() ){
    push @{$_->[1]},$dblink; # many links per id
  }
}
$sth2->finish;

# process each id-dblink pair
for (@$records){
  my $id = $_->[0];
  for my $dblink (@{$_->[1]}){
    my $sql3 = << "SQL3";
  SELECT 1 FROM DUAL\@$dblink
SQL3
    
    my $sth3 = $localDB->prepare($sql3);
      
    if ($DBI::err){
      print "Error with PREPARE for $dblink\n";
      print $DBI::errstr."\n";
    } else {
      $sth3->execute();
      if ($DBI::err){  
        print "Error with EXECUTE for $dblink\n";
        print $DBI::errstr."\n";
      } else {
        my @f = $sth3->fetchrow_array;  
        print "id=$id dblink=$dblink : @f\n";
      }
    } 
  }
}
$localDB->disconnect;


sub _dbh {
  my $host = "hostname";
  my $sid  = 'sid';
  my $user = 'user';
  my $pwd  = 'password';
  my $dsn = "dbi:Oracle:host=$host;sid=$sid";
  my $dbh = DBI->connect($dsn, $user, $pwd, 
            { AutoCommit => 0,
              PrintError => 0,
              RaiseError => 0,
              TraceLevel => 0, # increase as req
            })  or die "$!";
  return $dbh
}
[download]