When the Entity Framework was first introduced developers could generate a model from an existing database.  This is called Database First development.  Then the next round of enhancements to the Entity Framework allowed the developer to create the model and then generate a database from the model.  This is called Model First development.  With the release of Entity Framework 4.1 developers can now develop their classes with all the properties and then generate a database from the classes.  This is called Code First Development.

Code first works great if you are the type of developer that thinks about the object model or business logic layer first.  You can build all your classes and test out functionality before building the data model.  You could consider using this type of approach at the beginning of a project when changes are happening rapidly and you want to get up and running with a prototype quickly.

This article will demonstrate how to use the new Code First features in Entity Framework 4.1 to create a database.  You must install Entity Framework 4.1 for these features to work.  You can download the setup file here.  The code for the sample can be found here.

The sample will create an Invoice class and a LineItem class.  From these two classes a database called Accounting will be generated with two corresponding tables.  The you'll be able to bind the records in the table to a GridView control and also Add, Update, and Delete the records in the database.  Finally, the sample will show you how to modify a database if the classes change.