How to make Input Parameter optional in sap hana

Hi folks,

I wanted to make input parameter optional i.e.

if I do not give any value in input parameter or if I give '0' then it should give all the rows corresponding to that column.

I tried to achieve this by applying filter expression:

if('$$input_param$$'='' or isnull('$$input_param$$')=1,"column_name",'$$inputparam$$')

But it is giving column store error.

Eagerly waiting for your replies.

Thank you!