EF

   public class Article
    {
       [Key]
       public int ID { get; set; }
       public string Title{get;set;}

       public int AuthorssID { get; set; }

       public Author Author { get; set; }
    }

    public class Author
    {
        [Key]
        public int ID{get;set;}

        [MaxLength(50),Required]
        public string Name { get; set; }

        public string Address { get; set; }

    }

CodeFirst生成的数据表：

 

约定是以类名加ID来为外键命名的，如果找不到类名加ID的属性，则会成一个这样的规则来做为外键名。

同时也可以强制加ForeignKey来标识外键

   public class NewArticle//ForeignKey 用来指示外键名为AuthorssID
    {
        [Key]
        public int ID { get; set; }
        public string Title { get; set; }
       
        public int AuthorssID { get; set; }

        [ForeignKey("AuthorssID")]
        public Author Author { get; set; }
    }

生成的表为：

===============================================================================

    public class Department
    {
        [Key]
        public int ID{get;set;}

        [MaxLength(50)]
        public string Name { get; set; }

        //public virtual List<Employee> EmployeeList { get; set; }
        public List<Employee> EmployeeList { get; set; }
    }

  public class Employee
    {
        [Key]
        public int ID { get; set; }

        [MaxLength(30)]
        public string Name { get; set; }
    }

生成的数据表：可看到自动为Employee 添 加了一个Department_ID的外键

 

添加一个virtual

    public class Department1
    {
        [Key]
        public int ID{get;set;}

        [MaxLength(50)]
        public string Name { get; set; }
        public virtual List<Employee1> EmployeeList { get; set; }
    }

    public class Employee1
    {
        [Key]
        public int ID { get; set; }

        [MaxLength(30)]
        public string Name { get; set; }
    }

生成的数据表：

 

==================================

    public class Department3
    {
        [Key]
        public int ID{get;set;}

        [MaxLength(50)]
        public string Name { get; set; }

        public virtual List<Employee3> EmployeeList { get; set; }
    }

    public class Employee3
    {
        [Key]
        public int ID { get; set; }

        [MaxLength(30)]
        public string Name { get; set; }

        public int DepartmentID{get;set;}

        [ForeignKey("DepartmentID")]
        public virtual Department3 Department { get; set; }
    }

 

综上看来，导航属性(Virtual)与生成表结构没有关系，只是用来标识在LazyLoading时才会有用得到。

接下来，接着试验。

/// <summary>
    /// 会员
    /// </summary>
    public class User 
    {
        /// <summary>
        /// 用户ID
        /// </summary>
        [Key, DatabaseGenerated(DatabaseGeneratedOption.None)]
        public Int64 UserId { get; set; }

        /// <summary>
        /// 用户名
        /// </summary>
        [Required]
        [StringLength(50)]
        public string NickName { get; set; }

        /// <summary>
        /// 渠道负责人ID
        /// </summary>
        public int ChannelId { get; set; }

        /// <summary>
        /// 达人用户级别
        /// </summary>
        public int UserRank { get; set; }

        /// <summary>
        /// 渠道负责人
        /// </summary>
        public virtual Channel Channel { get; set; }

        [NotMapped]
        public Guid Id { get; set; }
    }

/// <summary>
    /// 渠道
    /// </summary>
    public class Channel 
    {
        [Key]
        public int ChannelId { get; set; }

        /// <summary>
        /// 渠道名
        /// </summary>
        [StringLength(100)]
        [Required]
        public string ChannelName { get; set; }

        /// <summary>
        /// 是否可用
        /// </summary>
        public int IsActive { get; set; }

        [NotMapped]
        public Guid Id { get; set; }
    }

运行测试

                var vUser = db.User.FirstOrDefault(p => p.UserId > 0);
                Console.WriteLine(vUser.NickName);
                Console.WriteLine(vUser.Channel.ChannelName);///如果Channel不为Virtual则在此处会报错，除非用Include显示加载