Most of the time questions comes to our mind about EF 4.1 Code First whether or not can we use it with already available database? Simple answer is YES.
I have very few personal view on it. I have seen in most of my application development scenario, database gets designed and created before and then evolves as application and requirements. So I expect to use Code First with already created database.
This is how we can,
Step 1: We will go for the database-first approach and create our EDMX.
Step 2: Right click on the edmx and then choose “Add Code Generation Item…”
Step 3: Select “ADO.NET DbContext Generator”. Then delete the .edmx file from your project.
After that you need few small but important changes,
Change 1 : Add the connection string (if using SQL Server)
Change 2 : The tables you are using in your code (check all the DbSet<T> in your context) and add their corresponding onModelCreating code
Then your code should run without any trouble,