SQL 根据1列数字 求其他两列相加

P00481708010002 18 18
P00481708010002 20 20
根据的 P00481708010002 单号  上面的原始数据
最后变成 
P00481708010002 38 38
P00481708010002 38 38要保证两条数据还存在 不能整合为一条数据！！！！！！只是金额发生变化 都变成38原始代码  
     SELECT  cyhq_u_orderdish.ch_branchno as '店名',                      --店名   
  t_hq_branch_info.vch_company,
--(select t_hq_branch_info.vch_company from t_hq_branch_info) as '店名',
  cyhq_u_orderdish.ch_payno as '结算单号' ,                 
                   cyhq_u_orderdish.ch_billno as '开单号' , --开单号                      
                   cyhq_u_orderdish.ch_dishno as '品码', --品码
(SELECT vch_dishname FROM cybr_bt_dish WHERE ch_dishno = cyhq_u_orderdish.ch_dishno) as '品名', --品名                      cyhq_u_orderdish.num_price_org -(convert(decimal(10,2),cyhq_u_orderdish.num_price_org+num_price_add-   (cyhq_u_orderdish.int_discount*1.0/100*(cyhq_u_orderdish.num_price_org+num_price_add)))) as '实际金额' , cyhq_u_orderdish.num_price_org as '销售金额' ,  
                convert(decimal(10,2),cyhq_u_orderdish.num_price_org+num_price_add-   (cyhq_u_orderdish.int_discount*1.0/100*(cyhq_u_orderdish.num_price_org+num_price_add))) as '折扣金额' ,   
 cyhq_u_orderdish.num_price_add as '加价'
from cyhq_u_orderdish   left join t_hq_branch_info on t_hq_branch_info.ch_branchno = cyhq_u_orderdish.ch_branchno
where    cyhq_u_orderdish.ch_payno='P00481708010002'
其中  cyhq_u_orderdish.ch_payno 是P00481708010002       cyhq_u_orderdish.num_price_org是第一行18 第二行20