-- List for each continent and each possible number of items per purchase (in the range 1...10), the corresponding number of purchases. Only consider countries that are 100% located in their respective continents.

-- How do you treat the default case as showed in the instructions?
-- Expected Heading: RELATION {continent CHARACTER, qty INTEGER, cnt INTEGER}
-- How do you treat the case where a country is splitted into two continents?

SELECT continent.name AS continent, qty, COUNT(qty) AS cnt
FROM continent
JOIN Encompasses ON Encompasses.continent = continent.name AND Encompasses.percentage = 100.0
JOIN country ON country.code = Encompasses.country
JOIN province ON province.country = country.code
JOIN Purchases ON Purchases.province = province.ROWID
WHERE qty <= 10 AND qty >= 1 AND time > date((SELECT MAX(time) FROM Purchases),'-10 days')
GROUP BY continent.name, qty
;