登录验证问题，纠结一天了，来个高手给指点下，在线等！
我是新手，这段代码看一天了 ， 也没找到解决的问题，不知道是不是SQL 语句错误，代码如下，麻烦高手给指点下！不胜感激！
  protected void btn_ok_Click(object sender, EventArgs e)
    {
      
            if (this.tb_userid.Text.ToString() == "" & this.tb_password.Text.ToString() == "")
            {
                lb_msg.Text = "员工编号或密码不能为空";
            }
            else
            {
                string con = "provider=microsoft.jet.oledb.4.0;"; con += @"data source=f:\网站开发\DataBase\hrdata.mdb";
                OleDbConnection Olecon = new OleDbConnection(con);
                Olecon.Open();
              

                OleDbCommand olecmd = new OleDbCommand("SELECT * FROM [user] WHERE (user_id = "+this.tb_userid.Text.ToString()+" AND user_password = "+this.tb_password.Text.ToString()+")",Olecon);

                
                OleDbDataReader olddr = olecmd.ExecuteReader();
                
                if(olddr.Read())
                {
                    this.btn_ok.PostBackUrl = "Salary.aspx";
                    Olecon.Close();
                    Olecon.Dispose();
                    Session["userid"] = this.tb_userid.Text.ToString();
                }
                else
                {
                    Olecon.Close();
                    Olecon.Dispose();
                    this.lb_msg.Text = "账号密码错误";