Query to return each value only once

I have a table that is structured as:

coursedate_id number(4) PK

session_no     number(4)
start_time     date
end_time       date

The data looks like this:

10  202    21-Aug-2003 0800    21-Aug-2003 1200
11  202    22-Aug-2003 0800    22-Aug-2003 1200
12  202    23-Aug-2003 0800    23-Aug-2003 1200
13  203    01-Sep-2003 1330    01-Sep-2003 1430
14  204    02-Sep-2003 0830    02-Sep-2003 1200
15  204    03-Sep-2003 0830    03-Sep-2003 1200

I can run this query which will bring back only the first of repeated rows, but how can I change this to also return rows where the session_no is only used once?

select session_no, start_time from coursedate c1 where rowid not in
(select min(rowid) from coursedate c2

where c1.session_no = c2.session_no)

returns:
202 21-Aug-2003 0800
204 02-Sep-2003 0830

(session_no 203 is not returned because it only appears once in the
table)

My goal is to return each session number ONCE, with the start time, so the result would look like:

202  21-Aug-2003 0800 
203  01-Sep-2003 1330     
204  02-Sep-2003 0830 

What do I need to add to this query to get these results?

Thanks,
Dina Received on Fri Mar 28 2003 - 11:00:20 CST