asp.net 报错，求大神帮解决

 //这是业务类

      public class userService
        {
    public static bool addUser(int id,string username,string password,string name,string tel,string addr,string email){
        string myStr = ConfigurationManager.AppSettings["conStr"].ToString();
        SqlConnection myConn = new SqlConnection(myStr);
      string sqlstr = "insert into user (_id,_username,_password,_name,_tel,_addr,_email) values(" + id + "'" + username + "'" + "'" + password + "'" + "'" + name + "'" + "'" + tel + "'" + "'" + addr + "'" + "'" + email + "'" + ")";
      SqlCommand comm = new SqlCommand(sqlstr,myConn);
        if(myConn.State==ConnectionState.Closed){
            myConn.Open();
        }
       int records = Convert.ToInt32(comm.ExecuteNonQuery());
      if (records > 0)
      {
          return true;
      }
      else {
          return false;
      }
    }
    }
//这是对业务类的调用

    protected void btn_reg_Click(object sender, EventArgs e){
        bool flag = false;
        string userName = t_un.Text;
        string passWord = t_pwd.Text;
        string name = t_n.Text;
        string tel = t_tel.Text;
        string addr = t_add.Text;
        string email = t_email.Text;
       flag= userService.addUser(1,userName,passWord,name,tel,addr,email);
       if (flag == true)
       {
           Response.Write("添加成功");
       }
       else {
           Response.Write("添加失败");
       }
    }

报错截图
以前写Java就是这么干的，业务类与调用分开，不知道asp.net有啥要求，第一次写asp.net,求大神帮助

这个没有一定标准，一般你想怎样就怎样写，根据项目框架定，一般都会分层些。

是可以这样写的，，，，，，

最好参数查询