Most people would probably handle it with variables and actions. Make two variables and trigger an action when either is entered that selects all dates in the range.
I'd probably handle it with data. In addition to the calendar table, add a from date table and a to date table. Every date in the from date table should map to itself and every later date. Every date in the to date table should map to itself and every earlier date. Add calendar objects for the from date field and the to date field. Selecting a from date and to date will now automatically narrow down to that date range just based on QlikView's normal associative logic. Attached is an example of that approach. In case you're only using personal edition, here's the script:
[Calendar]: LOAD date(makedate(2010)+recno()-1) as Date AUTOGENERATE 365 ;
[FromDate]: LOAD Date as FromDate ,date(Date+iterno()-1) as Date RESIDENT [Calendar] WHILE date(Date+iterno()-1) < makedate(2011) ;
[ToDate]: LOAD Date as ToDate ,date(Date-iterno()+1) as Date RESIDENT [Calendar] WHILE date(Date-iterno()+1) > makedate(2009,12,31) ;
Well, I was unable to get it to work with a select action, because there's no "clear this field, then select" ability so far as I know. You can clear all fields, which might work for the example, but wouldn't be any good in the real world. So I resorted to doing the selection with a triggered macro:
sub DateRange set field = activedocument.fields("Date") field.clear field.select "=Date>=FromDate and Date<=ToDate" end sub
