The commercial vendors are also opening a second front by working to get support for their databases in application frameworks that are popular with open-source users. For example, Zend Technologies Ltd. last week released software that lets developers use the PHP scripting language to write applications that can interact with any of Oracle's flagship 10g databases.

"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, vice president of business development at Cupertino, Calif.-based Zend.

Oracle said hundreds of thousands of developers and students have downloaded its Oracle Database 10g Express Edition since the software was released for beta testing in October. The free database, known as XE, became generally available last week.

According to IBM, DB2 Express-C was downloaded about 50,000 times in the first two weeks after its release in late January.

In contrast, Version 5.0 of MySQL has been downloaded more than 6 million times since October, said Zack Urlocker, vice president of marketing at MySQL AB's U.S. offices in Cupertino. "Sure, the express versions are free, but they come with very significant limitations, especially the lack of support," he said. "No enterprise customer will go into production with a database that cannot be supported."