How can I get a list of the most recent tags in a wordpress database?

Question

I am not familiar with the wordpress schema at all and I need to get back a list, or array of the most recent tags from any post in the wordpress database.

I just need the data available on the home page so I can then manipulate it.

All the functions seem to be designed to work on a per-post basis.

(Wordpress really makes me feel sorry for frequent wordpress programmers.)

Answer 1

This ain't pretty, maybe a MySQL junkie can optimize it a little;

SELECT $wpdb->terms.term_id, $wpdb->terms.name, $wpdb->terms.slug
FROM $wpdb->terms
    INNER JOIN $wpdb->term_taxonomy ON ($wpdb->terms.term_id = $wpdb->term_taxonomy.term_id)
    INNER JOIN $wpdb->term_relationships ON ($wpdb->terms.term_id = $wpdb->term_relationships.term_taxonomy_id)
    INNER JOIN $wpdb->posts ON ($wpdb->term_relationships.object_id = $wpdb->posts.ID)
WHERE $wpdb->term_taxonomy.taxonomy = 'post_tag'
ORDER BY $wpdb->posts.post_date DESC

This basically joins the term, term taxonomy, term relationship and post tables together, getting terms that are of the taxonomy 'post_tag', and currently have a relation with a post, then ordering them by the post's date, descending.

You might get the same term in the result set multiple times, but I can't work out how to use GROUP BY or HAVING to fix this, without messing up the date order.

So an example might in use might be;

$tags= $wpdb->get_results($query); // $query being the above SQL
foreach ($tags as $tag) {
    if (!isset($stack[$tag->term_id]))
        $stack[$tag->term_id] = $tag;
}
print_r($stack); // should print an array of all tags, ordered by last used