Thank's for the answers.
The situation is the following:
Our application uses Oracle RDBS 10g and we need to migrate it for mobile use on a client-side DB.
Since SQLite and Berkeley DB support SQL92 and HyperSQL provides also Oracle styled syntax and functions probably it would be less effort for us to migrate our application to HyperSQL. I know that HyperSQL is not supported officialy by Oracle but perhaps there exist experiances anyway.
having worked on sql lite 10gr3 a lot i would STRONGLY recommend you NOT to incorporate any other db than those used in olite itself. many problems will occur, you will have no support and things will not work. bugs come out even for olite(personally i had found 3 from which 1 was major, and olite released them in 2 patches, one of each was dedicated to the bug i had encountered only).
therefore if you use a non supported db you will have issues.