Just commenting on Rudy's suggestion:
select ItemNo, Seq, ' ' from myTable
where Seq is NOT null
union all
select ItemNo, Seq, '**oops**' from myTable
where Seq IS null
order by 1
I do this as:
select ItemNo, IIF(IsNull(Seq),'**oops**',Seq) from myTable
order by ItemNo
That's in MS Access. In Oracle, use the NVL function.
-David