C#实现在购物车系统中生成不重复订单号的方法

#region 生成单据号
/// <summary>
/// 生成单据号
/// </summary>
/// <param name="pFromType"></param>
/// <returns></returns>
public static string GetFormCode(FormType pFromType)
{
 string formcode = "";
 switch(pFromType)
 {
 case FormType.CaiGou:
 {
  formcode = "CG";
  break;
 }
 case FormType.ChaiXie:
 {
  formcode = "CX";
  break;
 }
 case FormType.ChuKu:
 {
  formcode = "CK";
  break;
 }
 case FormType.LingLiao:
 {
  formcode = "LL";
  break;
 }
 case FormType.PeiChang:
 {
  formcode = "PC";
  break;
 }
 case FormType.RuKu:
 {
  formcode = "RK";
  break;
 }
 case FormType.ShengChan:
 {
  formcode = "SC";
  break;
 }
 case FormType.SunYi:
 {
  formcode = "SY";
  break;
 }
 case FormType.TuiHuo:
 {
  formcode = "TH";
  break;
 }
 case FormType.XiaoShou:
 {
  formcode = "XS";
  break;
 }
 case FormType.PeiSong:
 {
  formcode = "PS";
  break;
 }
 case FormType.ZengPin:
 {
  formcode = "ZP";
  break;
 }
 case FormType.FuKuan:
 {
  formcode = "FK";
  break;
 }
 case FormType.ShouKuan:
 {
  formcode = "SK";
  break;
 }
 }
 formcode += DateTime.Now.Year.ToString();
 formcode += DateTime.Now.Month.ToString().Length == 1?"0" + DateTime.Now.Month.ToString() : DateTime.Now.Month.ToString();
 formcode += DateTime.Now.Day.ToString().Length == 1?"0" + DateTime.Now.Day.ToString() : DateTime.Now.Day.ToString();
 formcode += DateTime.Now.Hour.ToString().Length == 1?"0" + DateTime.Now.Hour.ToString() : DateTime.Now.Hour.ToString();
 formcode += DateTime.Now.Minute.ToString().Length == 1?"0" + DateTime.Now.Minute.ToString() : DateTime.Now.Minute.ToString();
 formcode += DateTime.Now.Second.ToString().Length == 1?"0" + DateTime.Now.Second.ToString() : DateTime.Now.Second.ToString();
 if(DateTime.Now.Millisecond.ToString().Length == 1)
 {
  formcode += "00" + DateTime.Now.Millisecond.ToString();
 }
 else if (DateTime.Now.Millisecond.ToString().Length == 2)
 {
  formcode += "0" + DateTime.Now.Millisecond.ToString();
 }
 else
 {
  formcode += DateTime.Now.Millisecond.ToString();
 }
 return formcode;
}
#endregion