public static bool Login(string userName)
        {
            int    userId = int.Parse(userName);
            string sqlStr = string.Format("select * from Users where userID={0}", userId);
            var    result = SqlSeverProvider.ExecuteScalar(sqlStr);

            if (result != null)
            {
                return(true);
            }
            else
            {
                return(false);
            }
        }