Microsoft said it had "completed engineering work to enable SQL Server Compact Edition (SQL CE) database to work within ASP.NET applications," stated Scott.
"SQL CE is a free, embedded, database engine that enables easy database storage. SQL CE works with existing .NET-based data APIs, and supports SQL Server compatible query syntax. You can use existing data APIs like ADO.NET or ORMs like Entity Framework and NHibernate. You don't need to run setup or install database to use SQL CE.
You'll be able to easily deploy SQL CE based databases to a remote hosting account and use it to run light-usage sites and apps. As your site traffic grows you can then optionally upgrade database to use SQL Server Express, SQL Server or SQL Azure – without changing your code. SQL CE stores databases as files on disk (within files with .sdf file extension). You can store SQL CE database files within \App_Data folder of ASP.NET Web app - they don't need to be registered to use. SQL CE database engine then runs in-memory within your app. When your app shuts down, database is automatically unloaded.