Apache Derby

Apache Derby, an Apache DB subproject, is an open source relational database implemented entirely in Java and available under the Apache License, Version 2.0. Some key advantages include:

• Derby has a small footprint -- about 2.6 megabytes for the base engine and embedded JDBC driver. 
• Derby is based on the Java, JDBC, and SQL standards. 
• Derby provides an embedded JDBC driver that lets you embed Derby in any Java-based solution. 
• Derby also supports the more familiar client/server mode with the Derby Network Client JDBC driver and Derby Network Server. 
• Derby is easy to install, deploy, and use.

I used it while I was working with OpenJPA about which I will write a tutorial later.

1-Anyway, please download Derby from:

http://db.apache.org/derby/derby_downloads.html

2- In windows;

set DERBY_INSTALL=C:\Apache\db-derby-10.10.2.0-bin

3-In windows;

set CLASSPATH=%DERBY_INSTALL%\lib\derby.jar;%DERBY_INSTALL%\lib\derbytools.jar;.

4-In windows;

C:\> cd %DERBY_INSTALL%\bin 

C:\Apache\db-derby-10.10.2.0-bin\bin> setEmbeddedCP.bat

5- If you put the jars in your classpath; then you can run this comment from anywhere in your computer:

> java org.apache.derby.tools.ij

After this command you can create new databases, run sql files and sql statements etc...

for example: 

connect 'jdbc:derby:/home/bill/databases/MyDbTest';

disconnect;

!!! If you do not disconnect from the table, the java project running from Eclipse cannot connect to the Database and it throws exceptions.