H2 is an SQL database engine written in Java that implements the JDBC API. Embedded, server, and clustering modes are available. A browser based console application is included. The database has strong security features. Disk based and in-memory databases and tables are supported.
Liberty Data Base Connectivity is a JDBC driver that provides vendor-independent database access. With LDBC, applications will just work on all major databases without source code changes. It is based on ANSI SQL and JDBC. It is very easy to use and learn, small and fast, and based on standards.