select wp_users.user_nicename, wp_users.display_name, wp_users.ID, friends.id, (select meta_value from wp_usermeta where wp_usermeta.meta_key='sex' and wp_usermeta.user_id=wp_users.ID) as sex from friends inner join wp_users on wp_users.ID=friends.friend_id where user_id=11409
Subquery returns more than 1 row/index.php