C# asp.net 按年月日自动编号函数

//按年月日编号

protected string getnumber()
        {
            string id = "";
            Random ro = new Random(unchecked((int)DateTime.Now.Ticks));
            id = "XQJH" + DateTime.Now.ToString("yyyyMMdd") + ro.Next(0, 999).ToString("000");
            return id;
        }