tax_terms_where.php

<?php
/*
* Adds "tax_terms" to WP_Query()
*
* See: http://lists.automattic.com/pipermail/wp-hackers/2010-October/035258.html
*
* Author: Mike Schinkel (http://mikeschinkel.com)
*
*/

	header('Content-Type:text/plain');
	include "../wp-load.php";
	add_action('posts_where','tax_terms_where',10,2);

	$result = new WP_Query('post_type=show&tax_terms=genre:grunge,genre:alternate');
	foreach($result->posts as $post) {
		echo "{$post->post_title}\n";
	}

function tax_terms_where($where,$wp_query) {
	if (isset($wp_query->query)) {
		$query = $wp_query->query;
		if (is_string($query))
			parse_str($query,$query);
		if (is_array($query) && isset($query['tax_terms'])) {
			global $wpdb;
			$tax_terms = explode(',',$query['tax_terms']);
			foreach($tax_terms as $tax_term) {
				list($taxonomy,$term) = explode(':',$tax_term);
				$sql = <<<SQL
AND $wpdb->posts.ID IN (
	SELECT tr.object_id
	FROM $wpdb->term_relationships AS tr
	INNER JOIN $wpdb->term_taxonomy AS tt ON tr.term_taxonomy_id = tt.term_taxonomy_id
	INNER JOIN $wpdb->terms AS t ON tt.term_id = t.term_id
	WHERE tt.taxonomy='%s' AND t.slug='%s'
)
SQL;
				$where .= $wpdb->prepare($sql,$taxonomy,$term);
			}
		}
	}
	return $where;
}