MySQL Chief Executive Marten Mickos confirmed the acquisition attempt in an interview at the Open Source Business Conference here but wouldn't provide details such as when the approach was made or how much money Oracle offered.

He did, however, say why he turned down Oracle's offer: the desire to keep his company's independence. "We will be part of a larger company, but it will be called MySQL! Oracle didn't immediately comment on the acquisition offer.

Though it is increasingly diversified, Oracle's primary business is selling its own proprietary database software. MySQL, in contrast, is a leader among several companies trying to commercialize rival open-source products.

Oracle already has bought two small open-source database companies--Sleepycat on Tuesday and InnoDB in 2005. But its open-source ambitions clearly are larger; for example, BusinessWeek reported that Oracle is expected to acquire open-source application server maker JBoss.