数据库命名有账号和密码 SQL也没错 调试的时候 数据库打开时好的 SQL复制到数据库中也能查到数据 为什么一直是-1呢 ?  /// <summary>
        /// 查询登录
        /// </summary>
        /// <param name="muser"></param>
        /// <returns></returns>
        public int Login(Model.User muser)
        {
            try
            {
                conn.Open();
                string sql = string.Format("select count(*) from t_User where UserName='{0}' and UserPwd='{1}'", muser.UserName, muser.UserPwd);
                cmd = new SqlCommand(sql, conn);
                int num = cmd.ExecuteNonQuery();
                return num;
            }
            catch (Exception)
            {                throw;
            }
            finally
            {
                conn.Close();
            }
        }