I am trying to set a primary key on a table that is already popluated.
The table has more than 5000 records in it, and when I set the primary
key I get an error that says there are duplicate values in the table.
What I need is a sql statement that will show me what records in the
table are duplicated. This is what I have come up with so far in my
testing

select a.* from idptodn a, idptodn b
where (a.tdstamp = b.tdstamp);

but it returns all the records as well as the duplicate ones. I am
very new at SQL so the reason for this is a Mystery to me! The script
above is just a sample that I was testing with. In the real table
there are 6 fields and 5 of them are for the new primary key. Any help
would be great!!!