Yes, please have a look at the volunteer documentation on this site.
Let's say you want to join table "User" and table "Access", then this might look like the following finder definition for EJB "User":
, Access WHERE User.ObjID=Access.UserID AND ...
so the query definition starts after the implicit "SELECT * FROM ". Please check out the documentation.
Hope this helps
This looks like it's for BMP but what about for CMP?