A new query is issued after every selection.
They may be selected in any order and combination.
The Oracle response is fast enough to allow for this approach.
My older Ingres database had performance limitations.

Somtimes, the user is looking for records for a given year,
for a given department. But, since some departments only have 5-8 records/year,
just selecting the department is sufficient to provide the info needed. Other
departments may have 3-4,000 records per year. so that selection is important.