To model employees and access control groups, we need to first modify our existing data to account for hierarchies in regions, countries, and cities. We also need to add hotel chains and their hierarchies. We can then apply the same practices used in modeling hierarchies to model access groups.
We already have airports and cities, which are geographical entities. We can add a couple of other entities such as country and region.
Figure 7.1: Country and region
A country or a region is uniquely identified by its name.
We can represent the relationship between airports, cities, countries, and regions in the following way:
Figure 7.2: Regions, countries, cities, and airports