Maybe you've never run into this problem before but I have. And it's a pain in the butt when it happens. When you create your .dbml file in Visual Studio the connection string to the database is stored in a couple of different locations and none of them are in the web.config or app.config file.

You're ready to test or launch the site and want to change the connection string, but it isn't centralized and isn't really that easy to find.

Take a look here (http://goneale.com/2009/03/26/untie-linq-to-sql-connection-string-from-applic... for instructions on how to use the app.config or web.config file to store the connection string