Okay, Rupert. I guess I read your initial note too quickly... :-) Sorry about that.
I don't see how you could automate this type of checking into a single JPA interaction with the database. You could accomplish something like this with multiple SQL statements, but then the logic and locking is pretty much left up to you. (BTW, I didn't care for Quora's sign-in requirements, so I didn't actually read the reference you posted.) Good luck, Kevin On Tue, Jun 10, 2014 at 12:43 PM, Rupert Smith <rupertlssm...@googlemail.com > wrote: > On 10 June 2014 16:31, Kevin Sutter <kwsut...@gmail.com> wrote: > > > I think you are just describing a unique constraint for a column (other > > than the primary key). > > > Sadly not, it isn't simply a question of putting a unique constraint on > some columns. As I pointed out, in some cases a duplicate is allowed, in > others it is not. I could just re-arrange the database design, but I don't > own the design it is something that has been given to me. > > Consider the case where the criteria to allow an insert to happen is some > arbitrary query, not just a unique constraint. This can be accomplished > with a WHERE NOT EXISTS (SELECT ... the arbitrary insertion condition). How > can this be done with JPA/OpenJPA? > > Rupert >
