diff --git a/classes/Language.php b/classes/Language.php
index 8d0a66467..09817047d 100644
--- a/classes/Language.php
+++ b/classes/Language.php
@@ -345,7 +345,7 @@ class LanguageCore extends ObjectModel
 	 */
 	public function loadUpdateSQL()
 	{
-		$tables = Db::getInstance()->executeS('SHOW TABLES LIKE \''._DB_PREFIX_.'%_lang\' ');
+		$tables = Db::getInstance()->executeS('SHOW TABLES LIKE \''.str_replace('_', '\\_', _DB_PREFIX_).'%\_lang\' ');
 		$langTables = array();
 
 		foreach ($tables as $table)
diff --git a/install-dev/upgrade/php/update_order_canada.php b/install-dev/upgrade/php/update_order_canada.php
index eb33821ca..44cf10d42 100644
--- a/install-dev/upgrade/php/update_order_canada.php
+++ b/install-dev/upgrade/php/update_order_canada.php
@@ -26,8 +26,8 @@
 */
 
 function update_order_canada()
-	{
-	$sql ='SHOW TABLES LIKE "'._DB_PREFIX_.'order_tax"';
+{
+	$sql ='SHOW TABLES LIKE "'.str_replace('_', '\_', _DB_PREFIX_).'order\_tax"';
 	$table = Db::getInstance()->executeS($sql);
 
 	if (!count($table))
diff --git a/install-dev/upgrade/sql/1.4.0.2.sql b/install-dev/upgrade/sql/1.4.0.2.sql
index 90ac0c70a..c472041c4 100644
--- a/install-dev/upgrade/sql/1.4.0.2.sql
+++ b/install-dev/upgrade/sql/1.4.0.2.sql
@@ -45,7 +45,7 @@ UPDATE `PREFIX_cms` SET `id_cms_category` = 0;
 
 ALTER TABLE `PREFIX_category` ADD `position` int(10) unsigned NOT NULL default '0' AFTER `date_upd`;
 
-UPDATE `PREFIX_employee` SET `id_lang` = (SELECT `value` FROM `PREFIX_configuration` WHERE `name` LIKE "PS_LANG_DEFAULT");
+UPDATE `PREFIX_employee` SET `id_lang` = (SELECT `value` FROM `PREFIX_configuration` WHERE `name` = "PS_LANG_DEFAULT");
 
 ALTER TABLE `PREFIX_customer` ADD `note` text AFTER `secure_key`;
 
@@ -171,9 +171,9 @@ CREATE TABLE `PREFIX_product_group_reduction_cache` (
 ) ENGINE=ENGINE_TYPE DEFAULT CHARSET=utf8;
 
 ALTER TABLE `PREFIX_currency` ADD `iso_code_num` varchar(3) NOT NULL default '0' AFTER `iso_code`;
-UPDATE `PREFIX_currency` SET iso_code_num = '978' WHERE iso_code LIKE 'EUR' LIMIT 1;
-UPDATE `PREFIX_currency` SET iso_code_num = '840' WHERE iso_code LIKE 'USD' LIMIT 1;
-UPDATE `PREFIX_currency` SET iso_code_num = '826' WHERE iso_code LIKE 'GBP' LIMIT 1;
+UPDATE `PREFIX_currency` SET iso_code_num = '978' WHERE iso_code = 'EUR' LIMIT 1;
+UPDATE `PREFIX_currency` SET iso_code_num = '840' WHERE iso_code = 'USD' LIMIT 1;
+UPDATE `PREFIX_currency` SET iso_code_num = '826' WHERE iso_code = 'GBP' LIMIT 1;
 
 ALTER TABLE `PREFIX_country` ADD `call_prefix` int(10) NOT NULL default '0' AFTER `iso_code`;