How can display multiple values to single column?

WordPress Plugin Development: How can I make a sortable custom column of a custom post type listing table by custom expression?

• I'm trying to create a custom sortable column in a post listing table of a custom post type. The problem is that each column cell value is an expression of multiple meta values. I could display the calculated value in each cell but I could not find a way to sort the column. Say, each post of my custom post type has two meta keys, 'followers' and 'mentions'. I've created a column that displays the number of followers divided by the number of mentions. How can I make it sortable? (I could make it sortable but it does not sort it properly) It seems to be achieved by modifying the MySQL query with the post_clauses hook as introduced in the below articles. http://scribu.net/wordpress/sortable-taxonomy-columns.html http://wordpress.stackexchange.com/questions/109955/custom-table-column-sortable-by-taxonomy-query However, they are for taxonomy columns and not exactly what I'm looking for. I'm guessing that the part dealing with the 'orderby' array element needs to be adjusted for my needs but not sure how. $clauses['orderby'] = "GROUP_CONCAT({$wpdb->terms}.name ORDER BY name ASC) "; $clauses['orderby'] .= ( 'ASC' == strtoupper( $wp_query->get('order') ) ) ? 'ASC' : 'DESC';

• Answer:

  Okay this worked. if ( is_admin() && 'edit.php' == $GLOBALS['pagenow'] && isset( $_GET['post_type'] ) && 'my_post_type' == $_GET['post_type'] && isset( $_GET['orderby'], $_GET['order'] ) ) { add_filter( 'posts_clauses', 'modify_query_clauses', 10, 2 ); } function modify_query_clauses( $clauses, $query ) { global $wpdb; if ( isset( $query->query['orderby'] ) && 'custom_expression' == $query->query['orderby'] ) { $clauses['join'] .= "INNER JOIN {$wpdb->postmeta} AS m1 on {$wpdb->posts}.ID = m1.post_id "; $clauses['join'] .= "INNER JOIN {$wpdb->postmeta} AS m2 on {$wpdb->posts}.ID = m2.post_id"; $clauses['where'] .= " AND m1.meta_key = 'followers'"; $clauses['where'] .= " AND m2.meta_key = 'mentions'"; $clauses['orderby'] = "( m1.meta_value / m2.meta_value ) "; $clauses['orderby'] .= ( 'ASC' == strtoupper( $query->get('order') ) ) ? 'ASC' : 'DESC'; } return $clauses; }