I want to make a ranking system for countries, according to population. But what I want is filters for my ranking. The filters are 3 drop down select html tags:
- all countries (and the list of the countries in a drop down)
- all regions (generated automatically upon selecting a country), and
- all times (2 years , 4 years, 6 years).
The expected population is calculated from a table in the database.
The question is: is it better to calculate the population and store it in a table for each of the filters above? Or, calculate and display them on the spot? I'm confused how to make the system work.