MySQL

   MySQL 4.0 is a free, open-source database. The commercial packages aiming for reliability.  MySQL has features that are standard in the other database packages. It does not support stored procedures and triggers, nor does it offer built-in support for XML, OLAP, or constraints. But it includes innovations, like the ability to cache queries. Transactions are not a part of MySQL's default, but they are included in two newer table types.
   MySQL is its fundamentally simple. You administer the database using over a dozen command-line utilities, the most important of which is the mysql utility, an interactive shell for controlling and querying a database. Besides running SQL scripts in batch mode, the utilities let you "dump" the contents of a database in text format. ntents of a database in text format. Instead of using a separate backup and restore utility, MySQL lets you back up by archiving the raw data files, but it makes incremental backups almost impossible.
  In addition to MySQL's ease of use, high performance and reliability you can benefit from advanced features, management tools and technical support to develop, deploy and manage your MySQL applications.
  MySQL is the world’s most popular open source database, enabling the cost-effective delivery of reliable, high-performance and scalable Web-based and embedded database applications. Looking for a database, take a peak at My SQL.