use strict;
use DBI;

my @reg_num = qw/12345 98564 33234 112345 87564 2345678 938566 1234486
+ 223456 123488/;
my @month = qw/03 01 01 10 05 11 03 05 02 09/;

my $dbh = DBI->connect("DBI:ODBC:$myserver",$u, $p,);

my $sql = "select name, last_name, reg_num, month, year                           from members
           where year='2009' AND (";

for my $i (0 .. $#reg_num)
{ 
    $sql .= "reg_num = '$reg_num[$i]' AND month = '$month[$i]' ";
    $sql .= 'OR ' unless $i == $#reg_num;
}
$sql .= ')'; # don't forget the ) on the end of the SQL

my $sth = $dbh->prepare($sql, { RaiseError => 1 });
   $sth->execute();