// added upgrade files (sql and php) in new installer

install-new/upgrade/php/generate_order_reference.php

@@ -0,0 +1,17 @@
+<?php
+
+function generate_order_reference()
+{
+	// Get all orders
+	$orders = Db::getInstance()->executeS('SELECT id_order FROM '._DB_PREFIX_.'orders');
+	foreach ($orders as $order)
+	{
+		$random_ref = '';
+		for ($i = 0, $passwd = ''; $i < 9; $i++)
+			$random_ref .= substr('ABCDEFGHIJKLMNOPQRSTUVWXYZ', mt_rand(0,25), 1);
+		Db::getInstance()->execute('
+			UPDATE '._DB_PREFIX_.'orders
+			SET reference = \''.$random_ref.'\'
+			WHERE id_order = '.(int)$order['id_order']);
+	}
+}