Reporting Services :: Displaying Data In Parameter Dynamically

I want to set the default value of the parameter based on the query result, when the current_status parameter is set as "opened" I want a certain date value to be displayed in the next parameter (start date), if it is set as closed I want a different date value to be displayed in the next parameter (start date), so I created the dataset with the query given below and assigned the default value to the query fields start and end date, however my Report parameters are not changing as expected.

dataset query:

IF @current_status = 'Opened'
SELECT DISTINCT cast(DATEADD(yy, DATEDIFF(yy, 0, getdate()), 0) AS date) AS Start_Date1, cast(MAX(estcompletion_date) AS DATE) AS End_date
FROM  <Table Name>
ELSE IF @current_status = 'Closed'
SELECT      distinct  cast(DATEADD(yy, DATEDIFF(yy, 0, getdate()), 0) AS date) AS Start_Date1, cast(getdate() AS DATE) AS End_date FROM <Table Name>