public class User

   {

      public int ID { get; set; }

      public string UserName { get; set; }

      public string Passwd { get; set; }

      public virtual UserInfo UserInfo { get; set; }

   }

public class UserInfo

    {

        public int ID { get; set; }

        public string Name { get; set; }

        public string  Phone { get; set; }

        public virtual User User { get; set; }

        public int UserID { get; set; }

    }

//            modelBuilder.Entity
     
      ().ToTable("Users");            modelBuilder.Entity
      
       ().HasKey(u => u.ID);            modelBuilder.Entity
       
        ().ToTable("UserInfos");            modelBuilder.Entity
        
         ().HasKey(b => b.ID);            ////针对“用户不一定要有信息类，信息一定要有用户类”关系的设置            modelBuilder.Entity
         
          ().HasOptional(b => b.UserInfo)                .WithRequired(x => x.User);