When developing domain classes in Entity Framework using Code First Approach, the default code conventions creates a primary key of a property named “ID” or <ClassName>ID. But if you wanted to use another property as your primary key , you can use DataAnnotations and decorate the property using “Key” attribute.
What is more interesting is that you could actually create a composite primary key. All you need to do is use another attribute along with “Key”, namely, “Column”.
The above example creates a Table with a Composite Primary Key made up of Dept1 and Dept2. Entity Framework is surely letting the developers live in the comfort zone of Visual Studio rather than dig up SQL Server.