请问关于面向对像的写法以下哪一种好呢？

请问关于面向对像的写法以下哪一种好呢？数据表如下:staff表
id    name departmentid 
1      张三    1
2      李四    2
3      王五    1
...............
departmet表id  department
1    电脑部
2    会计部
3    行政部
............
用面向对像写程序时， 实体类modal 以下写法用哪个好呢?写法一:
class Staff
{
  int id;
  public Id
  {
    get{return id;}
  }  string name;
  public Name
  {
    set{name=value;}
    get{return name;}
  }  int departmentid;
  public DepartmetId
  {
    set{departmentid=value;}
    get{return departmentid;}
  }  public Staff(int id, string name, int departmentId)
  {
    this.id=id;
    this.name=name;
    this.departmentid=departmentid;
  }
}class Department
{
  int departmentid;
  public DepartmentId
  {
    get{return departmentid;}
  }  string departmentname;
  public DepartmentName
  {
    set{departmentname=value;}
    get{return departmentname;}
  }  
  public Staff(int departmentid, string departmentname)
  {
    this.departmentid=departmentid;
    this.departmentname=departmentname;
  }
}写法二:
class Staff
{
  int id;
  public Id
  {
    get{return id;}
  }  string name;
  public Name
  {
    set{name=value;}
    get{return name;}
  }  Department departmentinfo;
  public DepartmetInfo
  {
    set{departmentinfo=value;}
    get{return departmentinfo;}
  }  public Staff(int id, string name, Department departmentinfo)
  {
    this.id=id;
    this.name=name;
    this.departmentinfo=departmentinfo;
  }
}class Department
{
  int departmentid;
  public DepartmentId
  {
    get{return departmentid;}
  }  string departmentname;
  public DepartmentName
  {
    set{departmentname=value;}
    get{return departmentname;}
  }  
  public Staff(int departmentid, string departmentname)
  {
    this.departmentid=departmentid;
    this.departmentname=departmentname;
  }
}
我的程序是用三层结构写的，在写实体层类库是遇到这样的问题，请教一下各位应该选择写法一还是写法二呢？