Now that I'm feeling a bit more comfortable with LINQ to SQL and LINQ to XML, I really wanted to begin exploring the ADO.NET Entity Framework and LINQ to Entities.

I started by going to msdn.microsoft.com/data and installed the ADO.NET Entity Framework Beta 3 and ADO.NET Entity Framework Tools CTP 2 (for Beta 3).

At first glance, I didn't notice anything new being provided by the Tools CTP, so I started a simple C# Console Application. From the Add New Item menu, I noticed an ADO.NET Entity Data Model template. After adding the data model, you're asked if you would like to generate the model contents from a database, or create a new one. Considering that I didn't know what exactly went into the model, I went with the generated approach. You are then asked to create a connection or use an existing and give a name for the connection settings to be saved in the App.Config. You'll see that it creates an "Entity connection string".

metadata=.\Model1.csdl|.\Model1.ssdl|.\Model1.msl;provider=System.Data.SqlClient;provider connection string="Data Source=LOCALHOST;Initial Catalog=Northwind;Integrated Security=True"

Finally you are able to choose the database objects (tables, views, stored procedures) to include within your model and give a name for the model namespace. Once generated, you'll find a ".edmx" file with an associated Designer class within the solution. The edmx Model appears similar to the reverse engineered tables, but also there are different types associated with each entity. In fact, each of these entities are classes that were generated to represent the data structure. Along with the scalar values of the associated table (i.e. Customers.Address), you'll notice "Navigation Properties" representing collections of related entities.

Notice the Orders and Products collections associated to the Order_Details entity? Ok, this is very interesting stuff that I'll explore more a little later. I want to see the what's changed for ADO.NET!

I decided to start simple. Suppose I wanted to see a list of customers who haven't made any purchases. Maybe we should send them some coupons! So, I'm thinking I'll create a database connection and execute a query using LINQ against the connection. Well..

Along with my Entity Types and Associations that were created with my model, I also have what's called an EntityContainer called NorthwindEntities that contains Entity Sets and Association Sets (and optionally imported functions). Again, further exploration required, but let's see what we can do with this EntityContainer.

Notice the Orders entity collection associated with the cus object. I didn't write any query or join to do that!