static public bool DeleteCalendar(DdCalendarExt item, RevisionInfo revisionInfo)
    {
      DaCalendar da = new DaCalendar(DataStore.DbConnection);
      bool ok = da.DeleteById(item.Id);
      if (ok) AddChangeLog(da.TableName, item.Id, item.Timestamp, revisionInfo); //delete
	  return ok;
    }
 static public bool AddCalendar(ref DdCalendarExt item, RevisionInfo revisionInfo)
 {
   DaCalendar da = new DaCalendar(DataStore.DbConnection);
   da.Clear();
   da.DayDate = item.DayDate;
   da.DayNumber = item.DayNumber;
   da.EndOfPeriod = item.EndOfPeriod;
   da.InvoiceDue = item.InvoiceDue;
   da.Modified = item.Modified;
   da.ModifiedBy = item.ModifiedBy;
   da.PeriodNumber = item.PeriodNumber;
   bool ok = da.Insert();
   if (ok) AddChangeLog(da.TableName, da.Id, da.Timestamp, revisionInfo); //add
   if (ok) item = new DdCalendarExt(da.GetBuffer());
   return ok;
 }
 static public bool SaveCalendar(ref DdCalendarExt item, RevisionInfo revisionInfo)
 {
   DaCalendar da = new DaCalendar(DataStore.DbConnection);
   if (!da.GetById(item.Id)) return false;
   da.DayDate = item.DayDate;
   da.DayNumber = item.DayNumber;
   da.EndOfPeriod = item.EndOfPeriod;
   da.InvoiceDue = item.InvoiceDue;
   da.PeriodNumber = item.PeriodNumber;
   bool ok = true;
   if (da._IsModified)
   {
     da.Modified = DateTime.Now;
     da.ModifiedBy = Environment.UserName;
     ok = da.Save();
     if (ok) AddChangeLog(da.TableName, da.Id, da.Timestamp, revisionInfo);
     if (ok) item = new DdCalendarExt(da.GetBuffer());
   }
   return ok;
 }