同类别的产品销售记录各要一条最新时间的

szxt_Buy_Nums 是销售表，每个会员有多条销售记录

要求：每个会员只选取一条记录

select a.MemberID,a.ActiveTime from szxt_Buy_Nums a where    a.autoid 

in (select top 1 autoid from szxt_Buy_Nums where MemberID = a.MemberID
 order by autoid desc) order by autoid