redundant product_attribute queries

- when adding product there is no need to remove any attributes belonging to it
- when updating the product the attributes related to the product are already cleared with
```php
$this->db->query("DELETE FROM " . DB_PREFIX . "product_attribute WHERE product_id = '" . (int)$product_id . "'");
```
no need to issue more specific deletion queries inside the loop
```php
$this->db->query("DELETE FROM " . DB_PREFIX . "product_attribute WHERE product_id = '" . (int)$product_id . "' AND attribute_id = '" . (int)$product_attribute['attribute_id'] . "'");
``

upload/admin/model/catalog/product.php

@@ -24,8 +24,6 @@ public function addProduct($data) {
 		if (isset($data['product_attribute'])) {
 			foreach ($data['product_attribute'] as $product_attribute) {
 				if ($product_attribute['attribute_id']) {
-					$this->db->query("DELETE FROM " . DB_PREFIX . "product_attribute WHERE product_id = '" . (int)$product_id . "' AND attribute_id = '" . (int)$product_attribute['attribute_id'] . "'");
-
 					foreach ($product_attribute['product_attribute_description'] as $language_id => $product_attribute_description) {
 						$this->db->query("INSERT INTO " . DB_PREFIX . "product_attribute SET product_id = '" . (int)$product_id . "', attribute_id = '" . (int)$product_attribute['attribute_id'] . "', language_id = '" . (int)$language_id . "', text = '" .  $this->db->escape($product_attribute_description['text']) . "'");
 					}
@@ -153,8 +151,6 @@ public function editProduct($product_id, $data) {
 		if (!empty($data['product_attribute'])) {
 			foreach ($data['product_attribute'] as $product_attribute) {
 				if ($product_attribute['attribute_id']) {
-					$this->db->query("DELETE FROM " . DB_PREFIX . "product_attribute WHERE product_id = '" . (int)$product_id . "' AND attribute_id = '" . (int)$product_attribute['attribute_id'] . "'");
-
 					foreach ($product_attribute['product_attribute_description'] as $language_id => $product_attribute_description) {
 						$this->db->query("INSERT INTO " . DB_PREFIX . "product_attribute SET product_id = '" . (int)$product_id . "', attribute_id = '" . (int)$product_attribute['attribute_id'] . "', language_id = '" . (int)$language_id . "', text = '" .  $this->db->escape($product_attribute_description['text']) . "'");
 					}
@@ -692,4 +688,4 @@ public function getTotalProductsByLayoutId($layout_id) {
 
 		return $query->row['total'];
 	}
-}
+}