gistfile1

$get_ids = $DB_site->query("
    SELECT a.id, b.iidd
    FROM table_b , table_a
    WHERE table_b.iidd = table_a.iidd
        AND table_b.id = 0
");

while ($data = $DB_site->fetch_object($get_ids))
{
    $DB_site->query("update table_b set id = {$data->id} where iidd = {$data->iidd}");
}