Users waiting for Oracle to integrate and build upon its SleepyCat open source database have another free option.

The company has taken its Database 10g Express Edition (XE), a stripped-down, free version of its flagship database software, to general availability.

XE is exiting beta mode, where it received strong global support from several hundred thousand Java, .NET, PHP and Web developers and students.

Programmers use it to write database applications on Windows and Linux platforms, Oracle said in a statement.

For example, Oracle said Missouri State University computer science students use XE in their classes to get a better feel for the Oracle database through procedures, functions and triggers.

The software is built on the same code base as Oracle Database 10g Release 2 and is compatible with all of Oracle's database family of products. Oracle intended XE to have a simple upgrade path for users who wish to upgrade and get the bells and whistles associated with Database 10g standard and enterprise editions.

Database XE is available now on 32-bit Windows and a slew of Linux operating systems: Debian, Mandriva Linux 2006 Power Pack+, Novell's SUSE Linux Enterprise Server 9 and SUSE Linux 10, Red Hat Enterprise Linux 4, Red Hat Fedora and Ubuntu.

The software can be downloaded for free here.

Oracle, which acquired open source database concerns SleepyCat Software and InnoDB, is not the only vendor offering free versions of its popular database.

IBM and Microsoft also embarked on such a strategy.

The top three database makers presumably created free Express versions to counter the rise of popular open source database maker MySQL.

MySQL just bought Netfrastructure.