Entity Framework Code-First（9.4）：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; }
     
    [Required]
    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.

Entity Framework Code-First（9.4）：DataAnnotations - Required Attribute

原文：http://www.cnblogs.com/purplefox2008/p/5644138.html