unformatted.sql

SELECT  country.country_name_eng, SUM(CASE WHEN call.id IS NOT NULL THEN 1 ELSE 0 END) AS calls, AVG(ISNULL(DATEDIFF(SECOND, call.start_time, call.end_time),0)) AS avg_difference FROM country  LEFT JOIN city ON city.country_id = country.id LEFT JOIN customer ON city.id = customer.city_id LEFT JOIN call ON call.customer_id = customer.id GROUP BY  country.id, country.country_name_eng HAVING AVG(ISNULL(DATEDIFF(SECOND, call.start_time, call.end_time),0)) > (SELECT AVG(DATEDIFF(SECOND, call.start_time, call.end_time)) FROM call) ORDER BY calls DESC, country.id ASC;