WP_Query order result by date AND meta_value

Question

I have searched but not found an answer to my problem. I have posts with a meta key used for ordering. I want to order post by this value. If they have same value I want them to be ordered by date.

I guessed that this was the query to use:

new WP_Query( array(
    'post_type' => array ('post', 'aggregato'),
        'cat' => '-1',
        'posts_per_page' => 12,
        'orderby' => 'meta_value_num date',
        'order' => DESC, 
        'meta_key' => 'mb_home',
        'meta_query' => array(
                                array(
                                        'key' => 'mb_home',
                                        'value' => 0,
                                        'compare' => '!=',
                                )
                        ) 
        ));

(the 'cat' => '-1' is just another check to exclude a specific category)

Now, this query returns posts that has a 'mb_home' value different than 0. And it orders them by that value. BUT completely ignores 'date'. If I have two posts with same mb_home value and different dates, it just goes date ASC instead of date DESC as expected.

Any pointers? What am I doing wrong here?

EDIT: This is the dump.

SELECT SQL_CALC_FOUND_ROWS wp_posts.ID FROM wp_posts INNER JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id) INNER JOIN wp_postmeta AS mt1 ON (wp_posts.ID = mt1.post_id) WHERE 1=1 AND ( wp_posts.ID NOT IN ( SELECT object_id FROM wp_term_relationships WHERE term_taxonomy_id IN (1) ) ) AND wp_posts.post_type IN ('post', 'aggregato') AND (wp_posts.post_status = 'publish' OR wp_posts.post_author = 1 AND wp_posts.post_status = 'private') AND (wp_postmeta.meta_key = 'mb_home' AND (mt1.meta_key = 'mb_home' AND CAST(mt1.meta_value AS CHAR) > '0') ) GROUP BY wp_posts.ID ORDER BY wp_postmeta.meta_value+0,wp_posts.post_date DESC LIMIT 0, 12

Answer 1

While WordPress does currently support multiple orderby it doesn't actually support multiple order respectively.

This was fixed very recently, see ticket #17065 (Independent ASC/DESC in multiple ORDER BY statement.) and will be available in 4.0 release with new array syntax: 'orderby' => array( 'title' => 'DESC', 'menu_order' => 'ASC' ).