(SELECT `id` as `item_id`, "notification" as `item_type`, `date` as `timestamp` FROM `notifications` WHERE `bobject_id` IN ('.implode(',',$ids).')) UNION (SELECT `id` as `item_id`, "activity" as `item_type`, `date` as `timestamp` FROM `activities` WHERE `bobject_id` IN ('.implode(',', $followings) .') AND `is_public`=1) UNION (SELECT `id` as `item_id`, "message" as `item_type`, `timestamp_last_message` as `timestamp` FROM `message_dialogs` WHERE `bobject_user_1`='.$bobject_user_id.' OR `bobject_user_2`='.$bobject_user_id.') ORDER BY `timestamp` DESC