wp-all-posts-for-any-term-in-a-taxonomy.php

<?php
/* 
wp-all-posts-for-any-term-in-a-taxonomy.php

This is an example showing a hook used to add the ability to use "any" as a term to match all terms for a taxonomy.
It will run as a standalone file in the root of a WordPress 3.0 install with a URL that looks like:

   http://example.com/wp-all-posts-for-any-term-in-a-taxonomy.php

It was written to address this question: 
   
   http://lists.automattic.com/pipermail/wp-hackers/2010-July/033465.html

Be sure to edit it to change the values for $post_type and $taxonomy to match the ones you need.

*/
include "wp-load.php";
add_action('posts_where','my_posts_where',10,2);

//======[CHANGE THESE]=========
$post_type = 'portfolio_item';
$taxonomy = 'clients';
//=============================

$posts = new WP_Query("post_type=$post_type&taxonomy=$taxonomy&term=any&posts_per_page=-1");
if ( $posts->have_posts() ):
	while ( $posts->have_posts() ) : $posts->the_post(); ?>
		<h2 id="post-<?php the_ID(); ?>" <?php post_class(); ?>><?php the_title(); ?></h2>
		<?php //the_content(); 
	endwhile; 
endif; 

function my_posts_where($where,$query) {
	if (isset($query->query_vars['taxonomy']) && $query->query_vars['term']=='any') {
		global $wpdb;
		$tt = $wpdb->term_taxonomy;
		$tr = $wpdb->term_relationships;
		$where .= $wpdb->prepare(" AND {$wpdb->posts}.ID IN (
						SELECT object_id FROM $tr
						INNER JOIN $tt ON $tt.term_taxonomy_id = $tr.term_taxonomy_id
						WHERE $tt.taxonomy=%s) ",$query->query_vars['taxonomy']);
		$where = str_replace(' AND 0 ','',$where);
	}
	return $where;
}