date interval variable in calculation view

Hi,

My graphical calculation View is Table function -> Projection(). I want to filter data using variable as date (Interval). currently with single mandatory date filter using input parameters it is working fine.

I created date_from and date_to as input to my table function and handled using between operators. But how I can map this to calculation view variable (date interval) ?

If I have to make it optional then how to handle at SQL level ? Table function does not support select-option like ABAP.