Java EE (Java Enterprise Edition) General Discussion

Hello, I have a problem with JSP. I want to display a part of a DB-table like this: The table looks like the following:

product1 20 30
product1 30 40
product2 20 50
product2 30 30
product2 10 80
product3 30 30
product3 40 40

Allright, what I want to do is, that only the DIFFERENT products will show up on the screen, like this:

product1
product2
product3

So I made my SQL-query like this:
"SELECT DISTINCT productname FROM tablename"

The error message I get is "Invalid descriptor index"

When I leave out the "distinct", I won't get only the different products, but all of the rows....

What's wrong with this? Or do I have to change my SQL-query string ??