Query posts by custom taxonomy and sort by post_modified

Question

I try to query 5 posts in cpt 'vacancy'. Query is very complex. For first I need posts that belongs to custom taxonomy with ID 18 and sorted by 'post_modified', then - all other posts in cpt 'vacancy' also sorted by 'post_modified'. And all of this limited to 5 posts.

For now I use:

$query_hot = $wpdb->get_results("(SELECT * FROM wp_posts
WHERE post_type = 'vacancy' AND post_status = 'publish'
AND ID IN (SELECT object_id FROM wp_term_relationships WHERE
wp_term_relationships.term_taxonomy_id = 18)
ORDER BY post_modified DESC)
UNION
(SELECT * FROM wp_posts
WHERE post_type = 'vacancy' AND post_status = 'publish'
AND ID NOT IN (SELECT object_id FROM wp_term_relationships WHERE
wp_term_relationships.term_taxonomy_id = 18)
ORDER BY post_modified DESC) LIMIT 5");

It queries right posts, but not sorts by 'post_modified'. What I doing wrong?

Answer 1

The WP_Query function can be used on custom taxonomies and post types and is probably easier than querying the database directly. The following should do what your looking for:

<?php $query_hot = new WP_Query( array(
    'post_type' => 'vacancy',
    'field' => '18', // You can use the ID or slug here
    'orberyby' => 'modified',
    'posts_per_page' => 5
)); 
while($query_hot->have_posts()) : $query_hot->the_post(); ?>

     <!-- Whatever you want to show in your loop -->

<?php endwhile; wp_reset_postdata(); // reset the query ?>

See the Codex article on WP_Query for more.