属性问题

Question

有两个窗体，一个类，窗体里面是propertyGrid控件，我在第一个窗体里面设置了propertyGrid控件的值，然后到第二个窗体的时候值又空了。
看代码。
Customer类： class Customer
    {
        private string _name;
        private int _age;
        private DateTime _dateOfBirth;
        private string _SSN;
        private string _address;
        private string _email;
        private bool _frequentBuyer;        [CategoryAttribute("ID Settings"), DescriptionAttribute("客户名")]
        public string Name
        {
            get
            {
                return _name;
            }
            set
            {
                _name = value;
            }
        }
        [CategoryAttribute("ID Settings"), DescriptionAttribute("Social Security Number of the customer")]        public string SSN
        {
            get
            {
                return _SSN;
            }
            set
            {
                _SSN = value;
            }
        }
        [CategoryAttribute("ID Settings"), DescriptionAttribute("Address of the customer")]
        public string Address
        {
            get
            {
                return _address;
            }
            set
            {
                _address = value;
            }
        }
        [CategoryAttribute("ID Settings"), DescriptionAttribute("Date of Birth of the Customer (optional)")]
        public DateTime DateOfBirth
        {
            get { return _dateOfBirth; }
            set { _dateOfBirth = value; }
        }
        [CategoryAttribute("ID Settings"), DescriptionAttribute("Age of the customer")]
        public int Age
        {
            get { return _age; }
            set { _age = value; }
        }
        [CategoryAttribute("Marketting Settings"), DescriptionAttribute("If the customer has bought more than 10 times, this is set to true")]
        public bool FrequentBuyer
        {
            get { return _frequentBuyer; }
            set { _frequentBuyer = value; }
        }
        [CategoryAttribute("Marketting Settings"), DescriptionAttribute("Most current e-mail of the customer")]
        public string Email
        {
            get { return _email; }
            set { _email = value; }
        }
        public Customer() { }Form1：
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        Customer bill = new Customer();        private void Form1_Load(object sender, EventArgs e)
        {
           
            propertyGrid1.SelectedObject = bill;
        }        private void button1_Click(object sender, EventArgs e)
        {
            bill.Age = int.Parse(textBox1.Text);
            
            //bill.Age = 50;
            bill.Address = "autocenter";
            bill.DateOfBirth = Convert.ToDateTime("1987-07-02");
            bill.SSN = "123-456-77988";
            bill.Email = "[email protected]";
            bill.Name="js";
            propertyGrid1.SelectedObject = bill;
            
        }        private void button2_Click(object sender, EventArgs e)
        {
            bill.Age = int.Parse(textBox1.Text);
            bill.Age = 50;
            bill.Address = "autocenter";
            bill.DateOfBirth = Convert.ToDateTime("1987-07-02");
            bill.SSN = "123-456-77988";
            bill.Email = "[email protected]";
            bill.Name = "js";
            Form2 f2 = new Form2();
            f2.ShowDialog();
            bill.Age = int.Parse(textBox1.Text);
        }
    }
}Form2：        public Form2()
        {
            InitializeComponent();
        }
        Customer bill2 = new Customer();        private void Form2_Load(object sender, EventArgs e)
        {
            propertyGrid1.SelectedObject = bill2;
            label1.Text = bill2.Age.ToString();
        }
    }
}

Answer 1

    public static ReportType getType(string name)
    {
        ReportType type = new ReportType();
        if (name!= null)
        {
            SqlConnection conn = new SqlConnection(Constant.ScheduleReport_CONNSTR);
            string sqlStr = Constant.DBType_Select;
            SqlParameter[] paramter = {
                                       new SqlParameter( "@NAME",SqlDbType.VarChar)
                                     };
            paramter[0].Value = name;
            using ( SqlDataReader dr=SqlHelper.ExecuteReader(CommandType.Text,sqlStr,paramter))
            {
                if (dr.Read())
                {
                    type.DB_TYPE = dr["DB_TYPE"].ToString();
                    type.SERVER = dr["SERVER"].ToString();
                    type.QUERY_SQL = dr["QUERY_SQL"].ToString();
                    type.DELETE_SQL = dr["DELETE_SQL"].ToString();
                    type.PENDING_SQL = dr["PENDING_SQL"].ToString();
                    type.RESUME_SQL = dr["RESUME_SQL"].ToString();
                    type.DB_NAME = dr["DB_NAME"].ToString();
                }            }
       }
       return type;    }
}    public class ReportType 
    {
        public ReportType()
        {}
      private string _db_type =string.Empty;
      private string  _server= string.Empty;
      private string _query_sql=string.Empty;
      private string _delete_sql=string.Empty;
      private string _pending_sql = string.Empty;
      private string __resume_sql = string.Empty;
       private string _db_name = string.Empty;        public string DB_TYPE 
        {
            get { return _db_type; }
            set { _db_type = value; }
        }
        public string SERVER
        {
            get { return _server; }
            set { _server = value; }
        }
        public string QUERY_SQL
        {
            get { return _query_sql; }
            set { _query_sql = value; }
        }
        public string DELETE_SQL
        {
            get { return _delete_sql; }
            set { _delete_sql = value; }
        }
        public string PENDING_SQL
        {
            get { return _pending_sql; }
            set { _pending_sql = value; }
        }
        public string RESUME_SQL
        {
            get { return __resume_sql; }
            set { __resume_sql = value; }
        }
        public string DB_NAME
        {
            get { return _db_name; }
            set { _db_name = value; }
        }    }

Answer 2

Form2：        public Form2(Customer p_Bill) 
        { 
            InitializeComponent(); if(p_Bill==null)
{
bill2=new Customer();
}
else
{
bill2=p_Bill
}
                    } 
        Customer bill2 ;
Form1里修改
Form2 f2 = new Form2(bill);