You can’t actually drag and drop a SQL Compact Edition 3.5 database to the LINQ to SQL designer. But it is very easy to create the classes and work beautifully. Fire up a VS08 prompt and find the SDF file that your database is stored in, then run the following command:

Prompt: SqlMetal /code:DotNetBooksDB.cs /pluralize /namespace:Books.Client.Library.Store.SqlCe dotNetBooks.sdf
Microsoft (R) Database Mapping Generator 2008 version 1.00.21022
for Microsoft (R) .NET Framework version 3.5
Copyright (C) Microsoft Corporation. All rights reserved.

The parameters are simple.

/code = the path where you would like to save the generated code.

/pluralize = changes the table book into books so you can write code like this: var x = from b in _ctx.Books (just looks a bit nicer)

/namespace = which namespace would you like your classes to have

and finally the path to the sdf file.

There is no output, but if you run the command your csharp should have been generated and just include that file into your project (and switch the project to .net Framework 3.5).