const string DEFSTR = "";
        /// <summary>
        /// 根据一个类型，获取其默认值，数字默认是为0，字符串默认值为一个空字符串
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <returns></returns>
        static T GetDefault<T>()
        {
            T t = default(T);
            //如果是字符串类型，则返回一个空字符串
            if (DEFSTR is T)
            {
                return (T)((object)DEFSTR);
            }
            return t;
        }

/// <summary>
        /// 获取一个DataRow某列的值
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="dr"></param>
        /// <param name="name"></param>
        /// <returns></returns>
        public static T GetValue<T>(DataRow dr, string name)
        {
            try
            {
                if (dr[name] == DBNull.Value)
                {
                    return GetDefault<T>();
                }
                else
                {
                    return (T)dr[name];
                }
            }//如果不存在这一列
            catch (ArgumentException ex)
            {
                return GetDefault<T>();
            }
        }
    }