select a, b
  from (select t.a, t.b, row_number() over(partition by t.a order by t.b) sx
          from X t)
 where sx = 1

------解决方案--------------------
探讨

怎么个死法，写法木有问题啊！
也可以使用分析函数处理

SQL code

select a, b
  from (select t.a, t.b, row_number() over(partition by t.a order by t.b) sx
          from X t)
 where sx = 1


------解决方案--------------------
就取每组的最小值么？  没这么麻烦吧
SQL code

select a,min(b) b
from tb
group by a

------解决方案--------------------
探讨

就取每组的最小值么？ 没这么麻烦吧

SQL code

select a,min(b) b
from tb
group by a