Charts with Parameter fields

[syncdba]

Hi,
I have a report with a chart & Fields(ID,Amount,Closemonth(Months(Aug05,Sept05.Nov05..)). I did GROUP BY on CloseMonth & SUM of Amount To get GROUP BY chart.If I Double-Click on a Month Vertical Bar, It gives me that month's Total amout. I wrote the SQL as:
select id,accountid,convert(money,amount) as Amount,closedate,
case
when closedate between '2005-07-31' and '2005-08-31' then 'August 2005'
when closedate between '2005-08-31' and '2005-09-30' then 'September 2005'
when closedate between '2005-09-30' and '2005-10-31' then 'October 2005'
when closedate between '2005-10-31' and '2005-11-30' then 'November 2005'
when closedate between '2005-11-30' and '2005-12-31' then 'December 2005'
when closedate between '2005-12-31' and '2006-01-31' then 'January 2006'
when closedate between '2006-01-31' and '2006-02-28' then 'February 2006'
when closedate between '2006-02-28' and '2006-03-31' then 'March 2006'
when closedate between '2006-03-31' and '2006-04-30' then 'April 2006'
when closedate between '2006-04-30' and '2006-05-31' then 'May 2006'
when closedate between '2006-05-31' and '2006-06-30' then 'June 2006'
when closedate between '2006-06-30' and '2006-07-31' then 'July 2006'
end as CloseMonth
from sfdcopportunity
WHERE ("sfdcOpportunity"."CloseDate">={ts '2005-08-01 00:00:00'}
AND "sfdcOpportunity"."CloseDate"<{ts '2006-07-31 00:00:01'})
order by closedate.

Now, I'm trying to create parameter Fields for this report. When I refresh this report, It will ask me about the following parameters.
1.Quarterly
2.Monthly
3.Enter ur own dates.
I'm not sure if its possible. I have SQl for Quarterly thing also. & I created a STATIC parameter for Dates also.