mysql中。第一种:先将金额按照一定要求原来的amount_money,case when rcd.material_code ='9801H00X' and expense_item ='收入' then rcd.amount_money-rcd.quantity*1.1 when rcd.material_code ='9801H00X' and expense_item ='成本' then rcd.amount_money-rcd.quantity*0.5257。...end as 新_amount_money拆分。拆分之后。求和这个sum(xin_amount_money)第二种。sum(原来_amount_money)-sum(quantity)**0.5257这2个结果为啥对不上?