Opencart. Функция getProductSpecials, модифировать запрос для вывода дополнительных товаров

Всем привет. Помогите разобраться.

Дано:

Имеется функция getProductSpecials в catalog/model/catalog/product.php Используется для вывода товаров на странице с акциями.

Задача:

Необходимо дополнительно вывести на странице с акциями, товары, у которых поле fake_special > 0 в oc_product

Код оригинал

$sql = "SELECT DISTINCT ps.product_id, (
SELECT AVG(rating) FROM " . DB_PREFIX . "review r1 
WHERE r1.product_id = ps.product_id AND r1.status = '1' 
GROUP BY r1.product_id) AS rating 
FROM " . DB_PREFIX . "product_special ps 
LEFT JOIN " . DB_PREFIX . "product p ON (ps.product_id = p.product_id) 
LEFT JOIN " . DB_PREFIX . "product_description pd ON (p.product_id = pd.product_id) 
LEFT JOIN " . DB_PREFIX . "product_to_store p2s ON (p.product_id = p2s.product_id) 
WHERE p.status = '1' 
AND p.date_available <= NOW() 
AND p2s.store_id = '" . (int)$this->config->get('config_store_id') . "' 
AND ps.customer_group_id = '" . (int)$this->config->get('config_customer_group_id') . "' 
AND ((ps.date_start = '0000-00-00' OR ps.date_start < NOW()) 
AND (ps.date_end = '0000-00-00' OR ps.date_end > NOW())) 
GROUP BY ps.product_id";

Получилось частично решить вопрос, объединив два SELECT с помощью UNION, дополнительные товары вывелись.

$sql = "SELECT ps.product_id, (
SELECT AVG(rating) FROM " . DB_PREFIX . "review r1 
WHERE r1.product_id = ps.product_id AND r1.status = '1' 
GROUP BY r1.product_id) AS rating 
FROM " . DB_PREFIX . "product_special ps 
LEFT JOIN " . DB_PREFIX . "product p ON (ps.product_id = p.product_id) 
LEFT JOIN " . DB_PREFIX . "product_description pd ON (p.product_id = pd.product_id) 
LEFT JOIN " . DB_PREFIX . "product_to_store p2s ON (p.product_id = p2s.product_id) 
WHERE p.status = '1' 
AND p.date_available <= NOW() 
AND p2s.store_id = '" . (int)$this->config->get('config_store_id') . "' 
AND ps.customer_group_id = '" . (int)$this->config->get('config_customer_group_id') . "' 
AND ((ps.date_start = '0000-00-00' OR ps.date_start < NOW()) 
AND (ps.date_end = '0000-00-00' OR ps.date_end > NOW())) 
GROUP BY ps.product_id
UNION
SELECT p.product_id, (
SELECT AVG(rating) FROM " . DB_PREFIX . "review r1 
WHERE r1.product_id = p.product_id AND r1.status = '1' 
GROUP BY r1.product_id) AS rating 
FROM " . DB_PREFIX . "product p
LEFT JOIN " . DB_PREFIX . "product_description pd ON (p.product_id = pd.product_id) 
LEFT JOIN " . DB_PREFIX . "product_to_store p2s ON (p.product_id = p2s.product_id) 
WHERE p.status = '1' 
AND p.fake_special > '0'
AND p.date_available <= NOW() 
AND p2s.store_id = '" . (int)$this->config->get('config_store_id') . "' 
GROUP BY p.product_id";

Но вылезла проблема с сортировкой, при ORDER BY p.sort_order например, вылезает ошибка Fatal error: Uncaught Exception: Error: Table 'p' from one of the SELECTs cannot be used in field list

Не получается объединить оба SELECT под одним ORDER BY.

UPDATE Готовое решение

$sql = "SELECT p.product_id, (
SELECT AVG(rating) FROM " . DB_PREFIX . "review r1 
WHERE r1.product_id = ps.product_id AND r1.status = '1' 
GROUP BY r1.product_id) AS rating 
FROM " . DB_PREFIX . "product p
LEFT JOIN " . DB_PREFIX . "product_special ps ON (ps.product_id = p.product_id) 
LEFT JOIN " . DB_PREFIX . "product_description pd ON (p.product_id = pd.product_id) 
LEFT JOIN " . DB_PREFIX . "product_to_store p2s ON (p.product_id = p2s.product_id) 
WHERE p.status = '1' 
AND p.date_available <= NOW() 
AND (ps.customer_group_id = '" . (int)$this->config->get('config_customer_group_id') . "' OR p.fake_special > '0')
AND (((ps.date_start = '0000-00-00' OR ps.date_start < NOW()) 
AND (ps.date_end = '0000-00-00' OR ps.date_end > NOW())) OR p.fake_special > '0') 
GROUP BY p.product_id";