diff --git a/install-dev/upgrade/php/category_product_index_unique.php b/install-dev/upgrade/php/category_product_index_unique.php
new file mode 100644
index 000000000..dd57620ce
--- /dev/null
+++ b/install-dev/upgrade/php/category_product_index_unique.php
@@ -0,0 +1,43 @@
+<?php
+/*
+* 2007-2011 PrestaShop
+*
+* NOTICE OF LICENSE
+*
+* This source file is subject to the Open Software License (OSL 3.0)
+* that is bundled with this package in the file LICENSE.txt.
+* It is also available through the world-wide-web at this URL:
+* http://opensource.org/licenses/osl-3.0.php
+* If you did not receive a copy of the license and are unable to
+* obtain it through the world-wide-web, please send an email
+* to license@prestashop.com so we can send you a copy immediately.
+*
+* DISCLAIMER
+*
+* Do not edit or add to this file if you wish to upgrade PrestaShop to newer
+* versions in the future. If you wish to customize PrestaShop for your
+* needs please refer to http://www.prestashop.com for more information.
+*
+*  @author PrestaShop SA <contact@prestashop.com>
+*  @copyright  2007-2011 PrestaShop SA
+*  @version  Release: $Revision$
+*  @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
+*  International Registered Trademark & Property of PrestaShop SA
+*/
+
+function category_product_index_unique()
+{
+	$res = true;
+	$key_exists = Db::getInstance()->executeS('SHOW INDEX
+		FROM `'._DB_PREFIX_.'category_product`
+		WHERE Key_name = "category_product_index"');
+	if ($key_exists)
+		$res &= Db::getInstance()->execute('ALTER TABLE 
+		`'._DB_PREFIX_.'category_product` 
+		DROP INDEX `category_product_index`');
+	$res &= Db::getInstance()->execute('ALTER TABLE 
+	`'._DB_PREFIX_.'category_product` 
+	ADD UNIQUE `category_product_index` (`id_category`, `id_product`)');
+
+	return $res;
+}
diff --git a/install-dev/upgrade/sql/1.4.7.0.sql b/install-dev/upgrade/sql/1.4.7.0.sql
index 4a4e1dc42..f38a89385 100644
--- a/install-dev/upgrade/sql/1.4.7.0.sql
+++ b/install-dev/upgrade/sql/1.4.7.0.sql
@@ -1,8 +1,6 @@
 SET NAMES 'utf8';
 
-ALTER TABLE `PREFIX_category_product` DROP INDEX `category_product_index`;
-ALTER TABLE `PREFIX_category_product` ADD UNIQUE `category_product_index` (`id_category`,`id_product`);
-
+/* PHP:category_product_index_unique(); */;
 
 CREATE TABLE IF NOT EXISTS `PREFIX_order_tax` (
   `id_order` int(11) NOT NULL,