Duplicates

Hi,

Is there a way to find duplicates in one field? For example my query has person_nbr and for each person_nbr on one day they could have used multiple payer_names. I want to be able to count each person_nbr one time but also I want to group by description(which is the name of the provider) and by payer name to see how many person's that the provider seen with each payer. My problem is that if the person had more than one payer they are counted twice. Is there some type of aggregate function to use the first payer in the list??

With PersonMIA (person_id,person_nbr,first_name,last_name,date_of_birth) as
(
select distinct person_id,person_nbr,first_name,last_name,date_of_birth from
(select count(*) as countenc,a.person_id,a.person_nbr,
a.first_name,a.last_name,
a.date_of_birth
from person a
join patient_encounter b on a.person_id = b.person_id
group by a.person_id,a.person_nbr,a.first_name,a.last_name,a.date_of_birth )tmp
where tmp.countenc <=1
)
select person_nbr,payer_name,first_name,last_name,description,year(create_timestamp),create_timestamp
from
(
select distinct c.description,tmp.person_id,tmp.person_nbr,tmp.first_name,
tmp.last_name,tmp.date_of_birth,d.payer_name,b.create_timestamp
from PersonMIA tmp
join person a on a.person_id = tmp.person_id
join patient_encounter b on a.person_id = b.person_id
join provider_mstr c on b.rendering_provider_id = c.provider_id
join person_payer d on tmp.person_id = d.person_id
where c.description = 'Leon MD, Enrique'
group by c.description,tmp.person_id,tmp.person_nbr,tmp.first_name,tmp.last_name,
tmp.date_of_birth,d.payer_name,b.create_timestamp
)tmp2
where year(create_timestamp) IN (2005,2006)
group by person_nbr,payer_name,first_name,last_name,description,create_timestamp

Thanks in Advance!
Sherri