Umbraco 4 now has built-in support for MySQL, MSSQL and VistaDB, as well as any other data source by using our provider model
Robust and flexible architecture
The new data layer in umbraco 4 is implemented using a provider-based model that makes it possible to use any SQL-enabled data source with umbraco. If the built-in support for Microsoft SQL Server, MySQL or VistaDB doesn't meet your needs, you can implement your own without modifying the umbraco core source. Simply inherit from an abstract class with all the base methods, modify it for your data source, drop the assembly (.dll) in the bin folder and change one line of configuration. Presto, umbraco can now work with Oracle, Access, DB2 or whatever you prefer.
Beautiful code, setting the standard
The new data layer is only one of the signs of the great new coding conventions that are being implemented in the umbraco business logic. Prepared for unit testing, following best practices from design patterns, and utilizing IDesign coding conventions, you get the benefit of the increasing code quality that is coming with umbraco 4.