How to find duplicate records by tree field?

I have a table named student, there are tree fields GradeID, ClassID, Seat
in it.
How can I fild the duplicate record by the tree fields?
Perhaps this will help.
SELECT GradeID, ClassID, Seat, count(*) as Rows
FROM Students
GROUP BY GradeID, ClassID, Seat
HAVING count(*) > 1
Roy Harvey
Beacon Falls, CT
On Thu, 5 Oct 2006 05:45:22 +0800, "ad" <flying@.wfes.tcc.edu.tw>
wrote:

>I have a table named student, there are tree fields GradeID, ClassID, Seat
>in it.
>How can I fild the duplicate record by the tree fields?
>
|||try this
select Count(*),GradeID, ClassID, Seat
from dbo.tablename
group by GradeID, ClassID, Seat
having count(*) > 1
the count will show you how many rows are duplicated for each instance...
/*
Warren Brunk - MCITP - SQL 2005, MCDBA
www.techintsolutions.com
*/
"ad" <flying@.wfes.tcc.edu.tw> wrote in message
news:Ox9to5$5GHA.3292@.TK2MSFTNGP02.phx.gbl...
>I have a table named student, there are tree fields GradeID, ClassID, Seat
>in it.
> How can I fild the duplicate record by the tree fields?
>
|||Thanks,
The tabe's primary is PID, how can I show the duplicate rows with PID.

> select Count(*),GradeID, ClassID, Seat
> from dbo.tablename
> group by GradeID, ClassID, Seat
> having count(*) > 1
> the count will show you how many rows are duplicated for each instance...
> --
> /*
> Warren Brunk - MCITP - SQL 2005, MCDBA
> www.techintsolutions.com
> */
>
> "ad" <flying@.wfes.tcc.edu.tw> wrote in message
> news:Ox9to5$5GHA.3292@.TK2MSFTNGP02.phx.gbl...
>