I’ve been teasing out details about the Windows Runtime (WinRT) here at Microsoft’s BUILD conference in Anaheim, California.
WinRT is the runtime for touch-friendly Metro-style apps, in effect Microsoft’s operating system for tablets, though it has a dual personality and full desktop Windows is also available.
Microsoft experts told me that there is no client for SQL Server or other network databases in WinRT. To access such databases, you have to create a web service and call that. This is similar to the Silverlight model. The .NET Framework in WinRT will support WCF RIA Services, which is one option for this.
If you only want to store and retrieve data locally, there seems to be a JET API, or you could use something like SQLite or roll your own simple database manager. HTML and JavaScript apps support IndexedDB. All these options read and write data to the app’s isolated storage; they do not enable free access to the file system.
LINQ (Language Integrated Query) is supported but of course that is only as useful as the data it can connect to.
Miguel has a pretty good basic overview write up
http://tirania.org/blog/archive/2011/Sep-15.html