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, a Web development and hosting firm in Round Rock, Texas.

On the other hand, Rajeev Kaula, a professor in Missouri State's information systems school, said Oracle's XE is easier to install than earlier "lite" Oracle databases and is helping him 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."

Savvica's Green said he has received a lot of inquiries from IT peers who previously weren't aware that they could install free versions of SQL Server, Oracle or DB2 as alternatives to open-source databases.

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