select * from suguanquan.订购单 a where 金额=
(select MAX(金额) from suguanquan.订购单 b where a.职工号=b.职工号)
order by 职工号 ASC;

select o1.* from 订单 a1
join 订单 a2      
    on(a1.职工=a2.职工)      
        group by o1.职工      
            having a1.金额=max(a2.金额);