Is there any way to specify optional parameters (such as when search parameters are provided from a form and not all parameters are required) in a named query when using Hibernate? I'm using a native SQL query, but the question is probably applicable to named HQL queries as well.
I'm pretty sure the answer to this is 'no', but I haven't found the definitive answer in the documentation yet.
AFAIK, there is no such thing so you'll have to write a dynamic query for this. Maybe have a look at this previous answer showing how to do this in HQL (that you can transpose to SQL) and also showing how the Criteria API makes it simpler and is thus better suited for this job in my opinion.
Update: (answering a comment from the OP) Working with a legacy database can be indeed tricky with Hibernate. Maybe you can use a dynamic native query and return non-managed entities though. But on the long run, things might get worse (I can't tell that for you). Maybe Hibernate is not the best choice in your case and something like iBATIS would give you the flexibility you need.