语句是select 采购单ID,SUM(采购金额) as 应付金额 from 采购明细 group by 采购单ID ; 和select 供应商.供应商名称,采购单.日期,采购单.采购单ID,采购单.状态,员工.员工名称 from 供应商,采购单,员工 where 供应商.供应商ID = 采购单.供应商ID and 采购单.员工ID = 员工.员工ID;