从一个表按照类型取top1如何实现

[coldljy]

表结构相关字段：
Id 标识 PK
TypeId 类型标识 FK
Sequence 顺序

要求按照顺序进行排序（可递增、可递减），取到每种类型的第一条记录
btw.性能第一

[lsxaa]

分组取最大
select a.*
from 表 a,(select typeid,max(sequence) as sequence from 表 group by typeid) b
where a.typeid=b.typeid and a.sequence=b.sequence

分组取最小
select a.*
from 表 a,(select typeid,min(sequence) as sequence from 表 group by typeid) b
where a.typeid=b.typeid and a.sequence=b.sequence

[zhaoanle]

select * from tbl a where id=(select top 1 id from tbl where typeid=a.typeid order by sequence)