将Decimal转换成字符串

///

        /// 时间型转化成string 类型
        ///

        ///
        /// yyyy-MM-dd类似的事件格式
        ///
        public static string ToStringDateTime(this DateTime param, string formart)
        {
            if (param == null) return "";
            if (param < new DateTime(2000, 1, 1)) return "";
            return param.ToString(formart);
        }