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 
                        )