text: CREATE OR REPLACE VIEW ne_10m_global_roads AS (
      SELECT geom, scalerank, featurecla as featureclass, type
      FROM ne_10m_roads WHERE continent <> 'North America'
      UNION ALL
      SELECT geom, scalerank, class as featureclass, type
      FROM ne_10m_roads_north_america
  );
  
  CREATE OR REPLACE VIEW road_z4 AS (
      SELECT *
      FROM ne_10m_global_roads
      WHERE scalerank <= 4
  );
  
  CREATE OR REPLACE VIEW road_z5 AS (
      SELECT *
      FROM ne_10m_global_roads
      WHERE scalerank <= 5
  );
  
  CREATE OR REPLACE VIEW road_z6 AS (
      SELECT *
      FROM ne_10m_global_roads
      WHERE scalerank <= 6
  );
  
  CREATE OR REPLACE VIEW road_z7 AS (
      SELECT *
      FROM ne_10m_global_roads
      WHERE scalerank <= 7
  );
  