wp query to use both author id and meta_query

The main problem is the AND logic that wordpress uses when creating a sql query.

This query will look for posts that have both author = 2 and meta query, additional_author that is LIKE 2.

Your best bet is to create your own query to achive this result.

I have created a static query for you to try

global $wpdb;

$sql="SELECT *";
$sql .= " FROM {$wpdb->prefix}posts AS p";
$sql .= " JOIN {$wpdb->prefix}postmeta AS pm ON p.ID = pm.post_id";
$sql .= ' WHERE (p.post_author = 2';
$sql .= ' OR (pm.meta_key = \'additional_author\' AND pm.meta_value LIKE \'%2%\'))';
$sql .= ' AND p.post_type = \'post\'';
$sql .= ' AND p.post_status = \'publish\'';
$sql .= ' GROUP BY p.ID';
$sql .= ' ORDER BY p.post_date DESC';
$sql .= ' LIMIT 5';

$results = $wpdb->get_results($sql);

print_r($results);

This is almost an exact copy of the query WordPress has built but with a small change, OR instead of AND.

Its a bit resource pricy because OR logic will create two tables to search in but it will do the work.

We don’t have to use $wpdb->prepare because all the sql is hardcoded by us, if you would like this query to be dynamic let me know and ill update the answer.