Apache Derby, an Apache DB subproject, is an open source relational database implemented entirely in Java.
Formerly known as IBM Cloudscape it is now included in Java 6 as Java DB.
Jackcess is a pure Java library for reading from and writing to MS Access databases. It is not an application. There is no GUI. It's a library, intended for other developers to use to build Java applications. Jackcess is licensed under the GNU Lesser General Public License. Take a look at our Frequently Asked Questions for more info.
jTDS is an open source 100% pure Java (type 4) JDBC 3.0 driver for Microsoft SQL Server (6.5, 7, 2000 and 2005) and Sybase (10, 11, 12, 15). jTDS is based on FreeTDS and is currently the fastest production-ready JDBC driver for SQL Server and Sybase. jTDS