Fixed for styleguide.
diff --git a/system/database/DB_driver.php b/system/database/DB_driver.php
index 4f2f491..b78f35a 100644
--- a/system/database/DB_driver.php
+++ b/system/database/DB_driver.php
@@ -816,7 +816,7 @@
 		}
 
 		// The query() function will set this flag to FALSE in the event that a query failed
-		if ($this->_trans_status === FALSE or $this->_trans_failure === TRUE)
+		if ($this->_trans_status === FALSE OR $this->_trans_failure === TRUE)
 		{
 			$this->trans_rollback();