念修改登陆用户的state状态以实现，异地登陆的限制，登陆+验证码已经实现，就状态修改不过来，求解

想修改登陆用户的state状态以实现，异地登陆的限制，登陆+验证码已经实现，就状态修改不过来，求解啊

C# code

求耐心的前辈指点啊，现在脑子有点乱修改状态的方法DAL层：public OAUsers UpdateStateByUserName(string where)        {            try            {                StringBuilder strSql = new StringBuilder();                strSql.Append("update OAUser");                strSql.Append(" set state=1");                if (where.Trim() != null)                {                    strSql.Append(" where username=@username");                }                SqlParameter[] para =                                  {                                   new SqlParameter("@username",SqlDbType.NVarChar,50)                                  };                OAUsers use = new OAUsers();                para[0].Value = use.State;                int res = DbHelperSQL.ExecuteSql(strSql.ToString(), para);                if (res > 0)                {                    return use; ;                }                else                {                    return null;                }            }            catch (Exception ex)            {                                throw new Exception(ex.ToString());            }        }修改状态的方法BLL层：        public OAUsers UpdateStateByUserName(string where)        {            return dal.UpdateStateByUserName(where);        }登陆按钮的代码：        protected void btnLogin_Click(object sender, EventArgs e)        {            var lgname=loginname.Text.Trim().ToString();            var lgpass=pass.Text.Trim().ToString();            if ( lgname.Length== 0 || lgpass.Length == 0)            {                Page.ClientScript.RegisterStartupScript(this.GetType(), "", "<script language=javascript> window.alert('用户名或密码不能为空！');</script>");            }            else            {                OAUserbll bll = new OAUserbll();                string sqlWher = " username= '"+lgname+"'";                DataSet ds = bll.GetUserByLoginName(sqlWher);                if (ds.Tables[0].DefaultView.Count > 0)                {                    if (lgpass == ds.Tables[0].Rows[0]["userpass"].ToString())                    {                        var check=txtVcode.Text.Trim().ToString().ToLower();                        var num = Session["VNum"].ToString().ToLower();                        if (check==num)                        {                            Session["lgname"] = lgname;                            HttpContext.Current.Response.Write("提交成功！");                            [color=#FF0000]bll.UpdateStateByUserName(sqlWher);[/color]                            Response.Write("<script>window.setTimeout('myfun()',1000)</script>");                            Response.Write("<script>function myfun() { window.location.href='index.aspx'}</script> ");                            Response.End();                        }                        else                        {                            Page.ClientScript.RegisterStartupScript(this.GetType(), "", "<script language=javascript> window.alert('验证码不正确！');</script>");                        }                                            }                    else                    {                        Page.ClientScript.RegisterStartupScript(this.GetType(), "", "<script language=javascript> window.alert('密码错误，登陆失败！');</script>");                        this.pass.Text = "";                    }                }                else                {                    Page.ClientScript.RegisterStartupScript(this.GetType(), "", "<script language=javascript> window.alert('该用户名不存在！');</script>");                    ClearPageAllTextBox();                                }            }        } 
 

C# code

      OAUsers use = new OAUsers();      para[0].Value = use.State;