Airspace database - adding country table and further customizing attribute dialog

Let's modify airspace database a bit. We have ctry_iso2 column in airspace table, because we want to to know in which country given airspace is. But what if we want to store more information about country? For example, link to authority that publishes aeronautical data or online version of aeronautical publication?

Customized dialog for airspace database - part 1

In this post we want to achieve customized attribute dialog that looks as follows:

Airspaces and PostGIS - introduction

The shapefile has been the only format for polygon 'part' of aviation data (airspaces). This format is handy, when we want  to store, manage or share data among user but has many limitations - and I don't mean only those specified here: