MySQL - World's most popular open source database
The MySQL database is the world's most popular open source database because of its consistent fast performance, high reliability and ease of use. It is used by individual Web developers as well as many of the world's largest and fastest-growing organizations to save time and money powering their high-volume Web sites, business-critical systems and packaged software -- including industry leaders such as Yahoo!, Alcatel-Lucent, Google, Nokia, YouTube, and Zappos.com. MySQL is part of the LAMP stack (Linux, Apache, MySQL, PHP / Perl / Python.) MySQL runs on more than 20 platforms including Linux, Windows, Mac OS, Solaris, HP-UX, IBM AIX.
MySQL Provides transactional and nontransactional storage engines, Executes very fast joins using an optimized nested-loop join, Uses a very fast thread-based memory allocation system, It is secure, scalable, supports several different character sets. MySQL client programs can be written in languages like C, C++, Eiffel, Java, Perl, PHP, Python, Ruby, and Tcl are available.
Professional edition and Commercial support is available.