Create 12. .py

Author: ortizfram

Introduction to Relational Databases in SQL/4. Glue together tables with foreign keys/12. .py

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+"""
+Join all the tables together
+In this last exercise, your task is to find the university city of the professor with the most affiliations in the sector "Media & communication".
+
+For this,
+
+you need to join all the tables,
+group by some column,
+and then use selection criteria to get only the rows in the correct sector.
+Let's do this in three steps!
+
+Instructions 3/3
+
+- Join all tables in the database (starting with affiliations, professors, organizations, and universities) and look at the result.
+- Now group the result by organization sector, professor, and university city.
+  Count the resulting number of rows.
+- Only retain rows with "Media & communication" as organization sector, and sort the table by count, in descending order.
+
+"""
+#1
+#-- Join all tables
+SELECT *
+FROM affiliations
+JOIN professors
+ON affiliations.professor_id = professors.id
+JOIN organizations
+ON affiliations.organization_id = organizations.id
+JOIN universities
+ON professors.university_id = universities.id;
+
+#2
+#-- Group the table by organization sector, professor ID and university city
+SELECT COUNT(*), organizations.organization_sector, 
+professors.id, universities.university_city
+FROM affiliations
+JOIN professors
+ON affiliations.professor_id = professors.id
+JOIN organizations
+ON affiliations.organization_id = organizations.id
+JOIN universities
+ON professors.university_id = universities.id
+GROUP BY organizations.organization_sector, 
+professors.id, universities.university_city;
+
+#3
+#-- Filter the table and sort it
+SELECT COUNT(*), organizations.organization_sector, 
+professors.id, universities.university_city
+FROM affiliations
+JOIN professors
+ON affiliations.professor_id = professors.id
+JOIN organizations
+ON affiliations.organization_id = organizations.id
+JOIN universities
+ON professors.university_id = universities.id
+WHERE organizations.organization_sector = 'Media & communication'
+GROUP BY organizations.organization_sector, 
+professors.id, universities.university_city
+ORDER BY count DESC;