What is the difference between code first and database first

The ADO.NET Entity Framework allows developers to choose any one approach among three possible approaches: Database First, Model First and Code First.

Database First: It is a more data-centric design that is based on an existing database. The Entity Framework is able to generate a business model based on the tables and columns in a relational database. The information about our database structure (store schema), our data model (conceptual model), and the mapping among them is stored in XML in an .edmx file.

Model First: In this approach, we don't have an existing database and the Entity Framework offers a designer that can create a conceptual data model. It also uses an .edmx file to store the model and mapping information. When the model has been created then the Entity Framework designer can generate the database schema that can be used to create the database.

Code First: Whether you have an existing database or not, you can code your own classes and properties that correspond to tables and columns and use them with Entity Framework without an .edmx file. In this approach Entity Framework does not leverage any kind of configuration file (.edmx file) to store the database schema, because the mapping API uses these conventions to generate the database schema dynamically at runtime.