Pagination with MySQL and PHP

pagination.php

<?php

/**
 * Handling offsets for articles in series using PHP and MySQL
 * pages is the table for articles
 */

$number_of_articles_per_page = 10;

$page = 1;

$page_offset = ($page - 1) * $number_of_articles_per_page;


// Query to get count of number of series in list of articles
$number_of_series = "SELECT COUNT(*) FROM (SELECT * FROM pages ORDER BY id LIMIT ".$page_offset.",".$number_of_articles_per_page.") as a where number_in_series = 1";

// Query to get all articles limited to the correct number per page

$articles = "SELECT * FROM pages WHERE series IN
  (SELECT series FROM
    (SELECT * FROM pages ORDER BY id LIMIT ".$page_offset.",".$number_of_articles_per_page.")
    AS a WHERE number_in_series = 1)
    OR id IN
    (SELECT id FROM (SELECT * FROM pages WHERE series = '' ORDER BY id LIMIT ".$page_offset.",".$number_of_articles_per_page.") as other_batch)";

?>