asp.net 日期流水号（急！在线等）

  protected void Button1_Click(object sender, EventArgs e)

    {

        staffModel staff = new staffModel();

        staff.Staffpwd = this.pwd.Text.ToString().Trim();

        string type = this.regtype.SelectedValue.ToString();

        //判断选择类型

        switch (type)

        {

            case "1":

                staff.Stafftype = "员工注册";

                break;

            case "2":

                staff.Stafftype = "教师注册";

                break;

            case "3":

                staff.Stafftype = "学生注册";

                break;

            case "4":

                staff.Stafftype = "家长注册";

                break;

            case "5":

                staff.Stafftype = "渠道注册";

                break;

        }

        staff.Staffname = this.people.Text.ToString().Trim();

        staff.Staffsex = int.Parse(this.sex.SelectedValue.ToString());

        staff.Staffinc = this.inc.Text.ToString().Trim();

        staff.Staffbonken = this.bonken.Text.ToString().Trim();

        staff.Staffphone = this.phone.Text.ToString().Trim();

        staff.Stafftel = this.tel.Text.ToString().Trim();

        staff.Staffmail = this.mail.Text.ToString().Trim();

        staff.Staffqq = this.qq.Text.ToString().Trim();

        staff.Staffaddress = this.address.Text.ToString().Trim();

        staff.Staffzipcode = this.zipcode.Text.ToString().Trim();

        staff.Staffnote = this.node.Text.ToString().Trim();

        staff.Staffdate = System.DateTime.Now;

        string year = System.DateTime.Now.ToString("yy");//截取时间年份



        //查询最大流水号

        DataSet ds = bll.Getmaxstaffcodeid();

        string id = ds.Tables[0].Rows[0][0].ToString();



        string newid;

        if (id == "" && id == null)

        {

            newid = "00000";

        }

        else

        {

            newid = Convert.ToString(Convert.ToInt32(id) + 1).PadLeft(5, '0');

        }

        staff.Staffcode = type + year + newid;//生成流水号

        if (this.yzm.Text.ToString().ToUpper() == this.IMGCODE1.Text)

        {

            if (eastelite.DIP.BLL.staffBll.addregister(staff))

            {

                Session["reg"] = staff;//存入session

                MailMessage mail = new MailMessage();

                staffModel s = Session["reg"] as staffModel;//接收session

                string mailfrom = System.Configuration.ConfigurationManager.AppSettings["servermailname"].ToString();

                string mailto = this.mail.Text.ToString().Trim();

                string mailpwd = System.Configuration.ConfigurationManager.AppSettings["servermailpwd"].ToString();

                mail.BodyFormat = System.Web.Mail.MailFormat.Html;

                mail.To = this.mail.Text;  //接受人的邮箱

                mail.From = mailfrom;  //你自己的邮箱(注意qq邮箱不行)

                mail.Subject = this.people.Text.ToString() + ",您好,感谢您注册****公司系统帐户";  //邮箱标题

                mail.Body = "尊敬的" + this.people.Text + ":<br>感谢您对于本系统的支持与关注！<br>您的注册信息如下：<br>系统帐号：<font color='red'>" + s.Staffcode + "</font><br>系统密码：<font color='red'>"

                    + this.pwd.Text + "</font><br>用户名：<font color='red'>" + this.people.Text + "</font><br>安全邮箱：<font color='red'>" + this.mail.Text

                    + "</font><br>帐号或其他相关问题请登录我们的官网咨询或留言.<br>谢谢您的关注！(请勿回复系统邮件)";

                mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusing", "2");

                mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", "1"); //stmp验证

                mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusername", mailfrom);

                mail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", mailpwd);

                SmtpMail.SmtpServer = "smtp.ym.163.com";  //企业代理邮件服务器

                SmtpMail.Send(mail);

                cleartext();//清空文本

                this.Page.ClientScript.RegisterStartupScript(this.GetType(), "str", "<script>window.open('regdetatile.aspx',target='_self');</script>");//弹出信息显示页面

            }

            else

            {

                this.Page.ClientScript.RegisterStartupScript(this.GetType(), "str", "<script>alert('抱歉。注册提交失败。请刷新后重新尝试！')</script>");

            }

        }

        else

        {

            this.Page.ClientScript.RegisterStartupScript(this.GetType(), "str", "<script>alert('验证码错误。请重新填写!')</script>");

        }

    }