find all users who lives in Paris using lat/lng and who visited the south of France within the last month

            
              
            
            SELECT u.*
FROM users AS u
JOIN visits AS v ON u.id = v.user_id
WHERE ST_Within(u.location, ST_GeomFromText('POLYGON((2.25 48.82, 2.41 48.82, 2.41 48.90, 2.25 48.90, 2.25 48.82))')) 
AND v.location <@ ST_MakeEnvelope(3.559, 41.303, 7.559, 46.235) 
AND v.visit_date >= (CURRENT_DATE - INTERVAL '1 month')

This SQL statement assumes that there are two tables: users and visits. The users table has columns id and location (which stores lat/lng as a geometry type). The visits table has columns user_id, location (also a geometry type), and visit_date.
The ST_Within function is used to find users who live in Paris. The coordinates for the polygon are roughly around Paris.
The ST_MakeEnvelope function is used to create a bounding box that roughly covers the south of France. The @< operator checks if the location of the visit is within this bounding box. The date of the visit is checked to be within the last month.