public class Test

    {

        //名称为 ID 的属性会自动映射为主键(自增长,唯一性,不为空)

        public long ID { get; set; }

    }

    public class Test

    {

        //Key 特性可将属性映射为主键(自增长,唯一性,不为空)

        [Key]

        public string Key { get; set; }

    }

    public class Test

    {

        //Key 特性可将属性映射为主键

        //使用 DatabaseGenerated 特性可取消主键自增长

        [Key]

        [DatabaseGenerated(DatabaseGeneratedOption.None)]

        public long ID { get; set; }

    }

    public class Test

    {

        // Guid 类型的主键默认没有自动生成，所以记得设置 DatabaseGenerated 特性

        [Key]

        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]

        public Guid ID { get; set; }

    }

    public class TestA

    {

        public long ID { get; set; }

        public string Name { get; set; }

        //导航属性, 子表集合

        public virtual ObservableCollection<TestB> TestBs { get; set; }

    }

    public class TestB

    {

        public long ID { get; set; }

        //外键, 命名约定为: 主表类名+主表主键名

        public long TestAID { get; set; }

        //导航属性, 主表类对象(与主表的导航属性可二选一)

        public virtual TestA TestA { get; set; }

        public DateTime DateTime { get; set; }

    }

    public class User

    {

        public int ID { get; set; }

        [Index(IsUnique = true)]

        [StringLength()]

        public string UserName { get; set; }

        public string DisplayName { get; set; }

    }