诚请各位大侠，求助，回答正确一定给分

                                 为什么实现不了修改的功能
数据库名：sanghui_data
表名：USER
字段名：(int主键)ID,(nvarchar)USERNAME,(nvarchar)USERID,(nvarchar)PASSWORD,(nvarchar)USERINFO,(nvarchar)PICTRUE,(varchar)LXR,(varchar)TEL,(varchar)FAX,(varchar)EMALL,(varchar)URL,(varchar)ADDRESS,(varchar)PASSCODE,(int)GRADE,(datetime)REGDATE

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class Redact_User : System.Web.UI.Page
{
    private static string user = "";
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            user = Request.QueryString["userid"];
        }
        this.txtUserid.Text = user;
    }
    DataBase.DBFactory clsDbFac = new DataBase.DBFactory();

    //保存修改以后的信息
    protected void btnSave_Click(object sender, EventArgs e)
    {
        string Userid = this.txtUserid.Text;//会员编号
        string UserName = this.txtUserName.Text;//会员名称
        string Userinfo = this.txtUserinfo.Text;//会员描述
        string Lxr = this.txtLxr.Text;//联系人
        string Tel = this.txtTel.Text;//电话
        string Fax = this.txtFax.Text;//传真
        string Emall = this.txtEmall.Text;//Emall地址
        string Url = this.txtUrl.Text;//Url地址
        string Address = this.txtAddress.Text;//住址
        string Passcode = this.txtPasscode.Text;//会员代码
        int Grade = Convert.ToInt32(this.ddlGrade.SelectedValue.ToString());//会员级别

        //判断会员编号是否存在
        string sql = "select count(*) from [USER] where USERID='" + this.txtUserid.Text + "'";
        string st = clsDbFac.ExecuteSqlScalar(sql);
        int intReturn = Convert.ToInt32(st);
        try
        {
            if (intReturn > 0)
            {

                string sql1 = "update [USER] set USERNAME='" + UserName + "',USERINFO='" + Userinfo + "',LXR='" + Lxr + "',TEL='" + Tel + "',FAX='" + Fax + "',EMAIL='" + Emall + "',URL='" + Url + "',ADDRESS='" + Address + "',PASSCODE='" + Passcode + "',GRADE=" + Grade + "  where USERID='" + Userid + "'";
                int i = clsDbFac.ExecuteSqlNonQuery(sql1);
                if (i > 0)
                {
                    Response.Write("<script>alert('会员修改成功！');</script>");
                }
                else
                {
                    Response.Write("<script>alert('会员修改失败！');</script>");
                }
            }
            else
            {
                Response.Write("<script>alert('会员编号不存在！');</script>");

            }
        }
        catch (Exception ee)
        {
            Response.Write(ee.Message);
        }
    }
} --------------------编程问答-------------------- 你自己设个断点走一下嘛，看是走到哪里跳出去了 --------------------编程问答-------------------- 调式一下看看进不进if   (intReturn   >   0)
--------------------编程问答-------------------- 我设了断点，可是不知道该哪里 --------------------编程问答-------------------- 主要是看它是否存在这个帐户. 断点设置在: int   intReturn   =   Convert.ToInt32(st);

跟踪. --------------------编程问答-------------------- int       intReturn       =       Convert.ToInt32(st); 这里没问题
--------------------编程问答-------------------- 调式慢慢来  我也看不出错误来细心点总会找到错误
看看赋值看看强转试试SQL --------------------编程问答-------------------- 多谢楼上的指导，我自己再调试看看 --------------------编程问答-------------------- GRADE="   +   Grade   +   "
改成
GRADE="   +   Grade.ToString()   +   " --------------------编程问答-------------------- 晕~

if   (intReturn   >   0) 

                        { 



                                string   sql1   =   "update   [USER]   set   USERNAME='"   +   UserName   +   "',USERINFO='"   +   Userinfo   +   "',LXR='"   +   Lxr   +   "',TEL='"   +   Tel   +   "',FAX='"   +   Fax   +   "',EMAIL='"   +   Emall   +   "',URL='"   +   Url   +   "',ADDRESS='"   +   Address   +   "',PASSCODE='"   +   Passcode   +   "',GRADE="   +   Grade   +   "     where   USERID='"   +   Userid   +   "'";

如果不存在重复ID号则intReturn=0 --------------------编程问答-------------------- 我刚刚试了一下，楼上的还是不行的 --------------------编程问答-------------------- intReturn > 0改为intReturn=0不是语法错误,是思路错误,
没有重复ID号时才更新啊
当大于零时,说明有重复ID号啊. --------------------编程问答-------------------- 问题不在于楼上所说的 --------------------编程问答-------------------- 我把文件发给你们，你们试着调试一下，，可以吗？

补充：.NET技术 ,  ASP.NET