43 lines
1.6 KiB
MySQL
43 lines
1.6 KiB
MySQL
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-- 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.
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-- Expected Heading: RELATION {country CHARACTER, province CHARACTER, abs INTEGER, prop FLOAT}
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-- How do you treat the default case as showed in the instructions?
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-- 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.
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SELECT name AS country, province, abs, prop
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FROM (
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SELECT name AS province, country, max(cnt) as abs, max(cnt)*1.0/sum(cnt) AS prop
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FROM(
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SELECT province, sum(qty) as cnt
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FROM Purchases
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WHERE product = 0
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GROUP BY province
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)
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JOIN Province ON province = Province.ROWID
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GROUP BY country
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)
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JOIN Country ON country = code
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;
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-- V2
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SELECT country.name, TMP.province, cnt AS abs, cnt*1.0/scnt AS prop
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FROM
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(
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SELECT province.country AS code, province.name AS province, COUNT(Purchases.qty) AS cnt
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FROM province
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LEFT JOIN Purchases ON Purchases.product = 0 AND Purchases.province = province.ROWID
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GROUP BY province.name
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) AS TMP
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JOIN (
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SELECT code, province, MAX(cnt) AS mcnt, SUM(cnt) AS scnt FROM (
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SELECT province.country AS code, province.name AS province, COUNT(Purchases.qty) AS cnt
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FROM province
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LEFT JOIN Purchases ON Purchases.product = 0 AND Purchases.province = province.ROWID
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GROUP BY province.name
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)
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GROUP BY code
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) AS F ON TMP.code = F.code AND TMP.cnt = F.mcnt
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JOIN country ON country.code = TMP.code
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;
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