how can l get the generic value list order by two filed

[hzz6222003]

Hi, every one
 
the entity modle as follows:
<entity entity-name="Pay" package-name="com.iit.yinshang.order" 
title="Yingshang payment YLCard pay">
  <field name="orderId" type="id-ne" />
  <field name="amount1" type="currency-amount" />
 <field name="amount2" type="currency-amount" />
  <prim-key field="orderId" />
 </entity>
 
how can l get the rocorders by the following sql:
select * from pay order by amount1+amount2 desc
 
Kind Regards
huang zhong zhou