-- One of the indicator is the distance between the capital city and the centre of the minimum bounding circle.
-- Here we create the minimum bounding circles.
DROP TABLE world_countries_mboundingcircle;
CREATE TABLE world_countries_mboundingcircle AS SELECT 
ccc.country_name, cc.fips_cntry, cc.city_name, ST_MinimumBoundingCircle(wcw.geom) geom
FROM capital_cities cc 
JOIN centroid_capital_cities ccc ON ccc.country_name = cc.country_name
JOIN world_countries_work wcw ON wcw.name = ccc.country_name;
