Query WordPress Posts without a custom meta key

gistfile1.aw

<?php
global $wpdb;

$meta_key = ''; // Enter your meta key

$querystr = "SELECT $wpdb->posts.ID
			FROM $wpdb->posts 
			WHERE $wpdb->posts.post_status = 'publish'
			AND $wpdb->posts.post_type = 'post'
			AND $wpdb->posts.ID NOT IN (
			    SELECT $wpdb->posts.ID
			    FROM $wpdb->posts
			    left join $wpdb->postmeta ON ($wpdb->posts.ID = $wpdb->postmeta.post_id)
			    WHERE $wpdb->posts.post_status = 'publish'
			    AND $wpdb->postmeta.meta_key = '".$meta_key."'
			)";


$pageposts = $wpdb->get_results($querystr, OBJECT);
?>