Missouri State University's information systems department and Web start-up Savvica don't have a lot in common apart from tight budgets. In recent years, that would have likely meant choosing a free open-source database such as MySQL or PostGres.

But last month, both eschewed open-source, opting instead for different commercial databases -- albeit the free, stripped-down versions.

"Everything's so much more solid now," said John Green, president of technology at the Toronto-based firm. Burgeoning Web traffic was causing Savvica's MySQL server to continually crash, and the company's e-learning applications were written in Java, which Green felt was not well supported by MySQL.

Instead of adding more MySQL servers, Green chose to roll out three of IBM's new DB2 Express-C databases managed by a load-balancing application from another Toronto firm, Xkoto Inc. "DB2 Express-C just feels like a much more profound piece of software," he said.

Using the open-standard JDBC interface, Savvica ported its data to DB2 Express-C from MySQL in less than a day, said Green.

Defections such as Savvica's hearten big commercial database vendors, including Microsoft, Oracle, IBM and even Sybase, which have all released free "express" databases in the past six months.

Despite more robust features, these hugely profitable databases have in recent years lost mind share -- and, increasingly, customers -- to their open-source counterparts. MySQL AB's success has epitomized the corporate revolt against the license and support fees charged for commercial databases.

But the free express databases are "significantly challenging the conventional wisdom about commercial vs. open-source databases," said Peter O'Kelly, an analyst at Burton Group.

The commercial database vendors are opening a second front by adding support for application frameworks popular with open-source users. On Tuesday, Zend Technologiesreleased software that enables developers to write applications interacting with the Oracle database in the PHP scripting language.

"IBM and Oracle are doing something similar to what MySQL has done: win the hearts and minds of developers by giving them easier access to technologies," said Mike Pinette, Zend's vice president of business development.

It's early, and the success of the big commercial database vendors at wooing back software developers -- who wield increasing influence over corporate buying decisions -- is not yet clear.

In the area of database instructional book sales, considered a good indicator of developer interest, sales of SQL Server how-to books have surpassed MySQL books this year, according to Roger Magoulis, director of research at leading publisher, O'Reilly Media. He believes that interest is due more to the general release of SQL Server 2005 last fall, rather than just its free edition -- especially as sales of Oracle or DB2 how-to books have inot ncreased significantly since the release of their free versions.

Sybase says its Adaptive Server Enterprise 15 express edition has been downloaded 45,000 times since its September release, with "a lot of that converting into business," according to Marty Beard, Sybase's senior vice president of corporate development and marketing.

Microsoft, which released its first free database, MSDE, back in 1999, did not immediately provide the number of downloads of SQL Server 2005 Express, which was released last October. But Oracle said hundreds of thousands of developers and students have downloaded Oracle XE since its beta release that same month. IBM's DB2 Express-C was made generally available only in late January.

In contrast, the latest 5.0 version of MySQL has been downloaded more than 6 million times since October, said Zack Urlocker, vice president of marketing at the Cupertino, Calif.-based firm. "Sure, the express versions are free, but they come with very significant limitations, especially the lack of support," Urlocker said. "No enterprise customer will go into production with a database that cannot be supported."

MySQL user Andy Meadows said he hasn't been tempted to switch.

"Unless it's a large CRM or identity management system, I've found MySQL to be robust and scalable enough," said Meadows, president of Live Oak Interactive Inc., an Austin-based Web development and hosting firm. And while he acknowledges that "you can do quite a bit within the parameters" of the express databases, he fears that vendors will pressure him to upgrade to an expensive supported version of their database.

Rajeev Kaula, a professor in Missouri State University's information systems department, said Oracle XE is easier to install than earlier "lite" Oracle databases and helps teach students to program more efficiently.

"Students who honed their skills on MySQL and PHP tend to treat databases only as a way of storing tables," Kaula said. Learning on Oracle XE, "they are realizing the power of transferring the business logic to the database itself."

Where MySQL proved popular with dot-coms needing to quickly deploy back-end databases, today's Web 2.0 start-ups are creating more complex Web applications, such as AJAX-based Web sites that may benefit from features such as more powerful XML data storage capabilities offered by the commercial databases, said Burton Group's O'Kelly.

And Savvica's Green said that contrary to the perception that Web 2.0 start-ups are wedded exclusively to the LAMP (Linux Apache MySQL and PHP/Python/Perl) application stack, he has gotten a lot of interest from peers who were unaware they could get free versions of SQL Server, Oracle or DB2.

"Frankly, these products are better," Green said. "As more people hear about them, I think they will start to eat MySQL's lunch."