Change supplier_id of stock orders to NULL

db/migrate/20181201000302_change_stock_supplier_to_null_in_order.rb

@@ -0,0 +1,11 @@
+class ChangeStockSupplierToNullInOrder < ActiveRecord::Migration
+  class Order < ActiveRecord::Base; end
+
+  def up
+    Order.where(supplier_id: 0).update_all(supplier_id: nil)
+  end
+
+  def down
+    Order.where(supplier_id: nil).update_all(supplier_id: 0)
+  end
+end