select top 10 * from [new] where newsclass='a1' order by updateTime desc union all select top 10 * from [new] where newsclass='a2' order by updateTime desc
select * from
(select top 10 * from [new] where newsclass='a1' order by updateTime desc union all select top 10 * from [new] where newsclass='a2' order by updateTime desc)
as temp
order by newsclass, updateTime desc;