SELECT * FROM `wp_postmeta` WHERE `post_id` BETWEEN 1 AND 5 AND `meta_key` LIKE 'pdf_url'
SELECT * FROM `wp_postmeta` AS m
LEFT JOIN `wp_posts` AS p ON `p`.`ID` = `m`.`post_id`
WHERE `p`.`ID` BETWEEN 1 AND 5 AND `p`.`post_status` = 'publish' AND `m`.`meta_key` LIKE '%pdf_url%'