SQL Server 2008 met COUNT() OVER
select *, c = count(1) over (partition by zip)
from tbl
order by c desc;
Als u de extra kolom niet hoeft te zien, kunt u de COUNT() OVER
verplaatsen clausule in de ORDER BY clausule.
select JobCode, Job1, Job2, Job3, zip
from tbl
order by count(1) over (partition by zip) desc;