Mike Matrigali wrote:
Out of curiousity what behavior does Hibernate expect when 2 nulls are inserted into a "unique" nullable column?
When you specify a unique constraint in hibernate, I'm pretty sure its only used by the schema export tools to generate a unique constraint when generating the DDL statements. That is, it doesn't care if you insert 2 nulls, it relies on the database to throw an exception. Things break when hibernate tries to generate a unique constraint on nullable columns in Derby. I guess its not smart enough to realize Derby (or any other db) doesn't support this. I have run into the same problem as I am working on a project that supports both MySQL and Derby and MySQL supports constraints on nullable columns, while Derby doesn't.
-Randy
