linfo2172-databases/P3/queries/query3.sql

43 lines
1.6 KiB
SQL

-- Determine for each country the province in which the total number of purchases of product 0 is the highest; list the name of the country, the name of the province, and the number of purchases, both absolute and as a proportion of the total number of purchases in that country.
-- Expected Heading: RELATION {country CHARACTER, province CHARACTER, abs INTEGER, prop FLOAT}
-- How do you treat the default case as showed in the instructions?
-- How do you treat the case where several provinces of a same country have the same total number of purchases of product 0? You should show all such provinces.
SELECT name AS country, province, abs, prop
FROM (
SELECT name AS province, country, max(cnt) as abs, max(cnt)*1.0/sum(cnt) AS prop
FROM(
SELECT province, sum(qty) as cnt
FROM Purchases
WHERE product = 0
GROUP BY province
)
JOIN Province ON province = Province.ROWID
GROUP BY country
)
JOIN Country ON country = code
;
-- V2
SELECT country.name, TMP.province, cnt AS abs, cnt*1.0/scnt AS prop
FROM
(
SELECT province.country AS code, province.name AS province, COUNT(Purchases.qty) AS cnt
FROM province
LEFT JOIN Purchases ON Purchases.product = 0 AND Purchases.province = province.ROWID
GROUP BY province.name
) AS TMP
JOIN (
SELECT code, province, MAX(cnt) AS mcnt, SUM(cnt) AS scnt FROM (
SELECT province.country AS code, province.name AS province, COUNT(Purchases.qty) AS cnt
FROM province
LEFT JOIN Purchases ON Purchases.product = 0 AND Purchases.province = province.ROWID
GROUP BY province.name
)
GROUP BY code
) AS F ON TMP.code = F.code AND TMP.cnt = F.mcnt
JOIN country ON country.code = TMP.code
;