查询 去重后的多列数据

select * from (

                    select row_number() over(order by  OrderId) as rownum ,OrderId,UserEmail from TOrder

                    where UserEmail IS NOT NULL AND UserEmail <> ''

               )kk

where kk.rownum in 

                      (

                            select  max(rownum) num from 

                            (

                            select row_number() over(order by  OrderId) as rownum ,OrderId,UserEmail from TOrder

                            where UserEmail IS NOT NULL AND UserEmail <> ''

                            )t

                            group by t.UserEmail 

                        )