请教一个SQL语句

[吹雪风]

有表test如下:
a varchar(2),b int

数据为:
a b
------------
x0 1
x2 2
x1 3
x2 4
x1 5

希望得到结果为:
x0
x2
x1

即按b排序,且去除掉已取到的数据,请问可以用一个SQL语句实现吗?

[paoluo]

?

Select a From test Group By a Order By Min(b)

[foolman888]

SELECT a FROM test GROUP BY a ORDER BY b asc

[chuifengde]

select a from test a where not exists(select * from test where a=a.a and b<a.b)

[vchao13]

没看明白

[fwacky]

declare @table table(a varchar(2),b int)

insert into @table
select 'x0' , 1 union all select
'x2' , 2 union all select
'x1' , 3 union all select
'x2' , 4 union all select
'x9' , 4 union all select
'x1' , 5
select * from @table

select distinct max( a) from @table group by b

希望得到结果为:

x0
x1
x2
x9

[ojuju10]

select a from test a
where not exists(select 1 from test where a.a=a and a.id>id)

[ojuju10]

select a from test a
where not exists(select 1 from test where a.a=a and a.id>id)
order by b