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PostGIS

Introduction
Geometry vs. Geography
Summary

Instruction

Perfect! As expected, the query in the previous exercise failed. What can we do in this situation? The answer is: casting to geometry, just like we did before:

SELECT 
  ST_Area(ST_Transform(
    boundaries::geometry,
    26910))/1000000 
FROM usa_states 
WHERE name = 'Alaska';

As usual, remember about to use the right SRID!

Exercise

Write a query that will make a single polygon around all US states. Use casting to geometry to obtain the correct result.

Stuck? Here's a hint!

Cast boundaries to ::geometry.

In the ST_Transform() function, use the SRID for the whole world – 4326.