How to create filter in IDT?

Dear Experts,

I have a requirement where I have to show webi user filter/prompt with two choices,
1) PAX
2) STAFF

where user can pick one or both.

Issue is that we differentiate PAX and STAFF on a given column in Database called STAFF_No. (Staff Number), for particular record if STAFF_No is null then we consider it as PAX else it is considered as STAFF.

if user selects PAX from prompt then it should show STAFF_No with null values, alternatively if user selects STAFF then it should show STAFF_No with values.

So how can I achieve it, whether in WEBI or in IDT?