select 标本号,(Select Top 1 指标值 from 表 as b Where b.标本号 = a.标本号 Order by 检验日期 Desc ) as 最终指标值 from 表 as a group by 标本号没设主键，否则就更方便了速度也会提高一个等级
select max(指标值) from 表 group by 指标
