假如现在是2002年1月，那么上个月是几几年几月呢，怎么计算呢？

Question

YourDate2 := IncMonth(YourDate, -1);

Answer 1

var
  PreYear,PreMonth: integer;
  YourDate: DateTime;PreYear:=YearOf(IncMonth(YourDate, -1));
PreMonth:=YearOf(IncMonth(YourDate, -1));

Answer 2

下面的是我在一个程序中写的一些代码，你可以参考一下就可以实现你想要的了：
workeryear:=strtoint(pyyear.Text) div 12;
        workermonth:=strtoint(pyyear.Text) mod 12;
        endyear:=strtoint(copy(datetostr(inDwdata.date),1,4))+workeryear;
        endmonth:=strtoint(copy(datetostr(inDwdata.date),6,2))+workermonth;
        if endmonth>12 then begin endyear:=endyear+1;endmonth:=endmonth-12;end;
        endday:=strtoint(copy(datetostr(inDwdata.date),9,2));
        tempyear:=endyear;
        case endmonth of
                4,6,9,11:   if endday=31 then endday:=endday-1;
                       2:   begin
                               if (tempyear mod 4)=0
                               then begin
                                      if endday=31 then endday:=endday-2;
                                      if endday=30 then endday:=endday-1;
                                    end
                               else begin
                                      if endday=31 then endday:=endday-3;
                                      if endday=30 then endday:=endday-2;
                                    end;
                            end;
        end;
        enddate:=inttostr(endyear)+'-'+inttostr(endmonth)+'-'+inttostr(endday);

Answer 3

我刚刚专门试过没有问提!!!给分吧!!!!procedure TForm1.Button1Click(Sender: TObject);
var
        year,month,day:word;
begin
        decodedate(strtodatetime(dxdateedit1.Text),year,month,day);
        if (month-1)>0 then
           label1.Caption:=inttostr(year)+'-'+inttostr(month-1)+'-'+inttostr(day)
        else
           label1.Caption:=inttostr(year-1)+'-'+inttostr(month)+'-'+inttostr(day);
end;

Answer 4

to linbee(linbee) ;
我在edit里输入2002-01-01不好使；

Answer 5

YourDate2 := IncMonth(YourDate, -1);
 .............incyear(yourdate,-1);
...............incday(yourdate,-1);
都可以

Answer 6

YourDate2 := IncMonth(YourDate, -1);
 .............incyear(yourdate,-1);
...............incday(yourdate,-1);
都可以