管理软件常常要查询本月和上月的数据，以下是自定义函数，取得本月和上月的最后一天。

查询时可以直接使用.如：

select * from 出货单 where 出货日期 beween GetPreMonthFirstDay() and  GetPreMonthLastDay()

Public Function GetThisMonthFirstDay()
    GetThisMonthFirstDay = DateSerial(Year(Date), Month(Date), 1)
End Function

Public Function GetThisMonthLastDay()
    LastDay = DateSerial(Year(Date), Month(Date) + 1, 0)
End Function

Public Function GetPreMonthFirstDay()
    GetPreMonthFirstDay = DateSerial(Year(Date), Month(Date) - 1, 1)
End Function

Public Function GetPreMonthLastDay()
    GetPreMonthLastDay = DateSerial(Year(Date), Month(Date), 0)
End Function