#!/opt/perl-5.20/bin/perl
use strict;
use warnings;
use DBI;
main();
exit;
sub main {
  my $dbh = DBI->connect or die "oops - $!\n";
  my $Customer_ID = 10;
  my $sql = "select customer_id from t where customer_id = ?";
  my $sth = $dbh->prepare($sql)  or die "oops - $!\n";
  my $rc  = $sth->execute($Customer_ID);
  while (my $rrow = $sth->fetch) { print $rrow->[0], "\n"; }
}