[#6665] Fixed comments

Author: wouterj

book/from_flat_php_to_symfony2.rst

@@ -254,10 +254,12 @@ an individual blog result based on a given id::
     function get_post_by_id($id)
     {
         $link = open_database_connection();
+
         $query = 'SELECT created_at, title, body FROM post WHERE  id=:id';
-        $statement = $pdo->prepare($query);
-        $statement->bindParam(':id', $id, PDO::PARAM_INT);
+        $statement = $link->prepare($query);
+        $statement->bindValue(':id', $id, PDO::PARAM_INT);
         $statement->execute();
+
         $row = $statement->fetch(PDO::FETCH_ASSOC);
 
         close_database_connection($link);