DataAnnotations - Required Attribute:

Required attribute can be applied to a property of a domain class. EF Code-First will create a NOT NULL column in a database table for a property on which we apply Required attribute. Note that it can also be used with ASP.Net MVC as a validation attribute.

Consider the following example.

using System.ComponentModel.DataAnnotations;
public class Student
    public Student()
    public int StudentID { get; set; }
    public string StudentName { get; set; }

As you can see in the above code, we have applied Required attribute to StudentName. So, Code First will create a NOT NULL StudentName column in the Student table as shown below.

dataannotations required attribute