上个月第一天：<%=dateadd("m",-1,year(date)&"-"&month(date)&"-1")%>
上个月最后一天：<%=dateadd("d",-1,year(date)&"-"&month(date)&"-1")%>
本月第一天：<%=year(date)&"-"&month(date)&"-1"%>
本月最后一天：<%=dateadd("d",-1,dateadd("m",1,year(date)&"-"&month(date)&"-1"))%>
下个月第一天：<%=dateadd("m",1,year(date)&"-"&month(date)&"-01")%>
下个月最后一天：<%=dateadd("d",-1,dateadd("m",2,year(date)&"-"&month(date)&"-01"))%>
