The Overall Average

Coddy'nin SQL Journey'sinin Temeller bölümünün bir parçası — ders 56 / 72.

Görev

Kolay

Mevcut tablolar ve sütunlar:
enom_gilpane: part_id, rpm, watt, size
castle_loctus: part_id, rpm, watt, size
honpan_bilopsa: part_id, rpm, watt, size
yurnol_qoltam: part_id, rpm, watt, size

Son olarak, her part_id için ortalama kaliteyi hesaplayın.

part_id avg_quality döndürün, avg_quality'ye göre azalan sırada sıralanmış.

Kendin dene

SELECT part_id, AVG(quality) AS quality
FROM (
    SELECT part_id, AVG(quality) AS quality
    FROM (
        SELECT part_id, (rpm * (watt + (SELECT AVG(watt) FROM enom_gilpane)) / size) as quality
        FROM enom_gilpane
    )
    GROUP BY part_id
    HAVING quality > AVG(quality)
    UNION ALL
    SELECT part_id, AVG(quality) AS quality
    FROM (
        SELECT part_id, (rpm * (watt + (SELECT AVG(watt) FROM castle_loctus)) / size) as quality
        FROM castle_loctus
    )
    GROUP BY part_id
    HAVING quality > AVG(quality)
    UNION ALL
    SELECT part_id, AVG(quality) AS quality
    FROM (
        SELECT part_id, (rpm * (watt + (SELECT AVG(watt) FROM honpan_bilopsa)) / size) as quality
        FROM honpan_bilopsa
    )
    GROUP BY part_id
    HAVING quality > AVG(quality)
    UNION ALL
    SELECT part_id, AVG(quality) AS quality
    FROM (
        SELECT part_id, (rpm * (watt + (SELECT AVG(watt) FROM yurnol_qoltam)) / size) as quality
        FROM yurnol_qoltam
    )
    GROUP BY part_id
    HAVING quality > AVG(quality)
)
GROUP BY part_id
ORDER BY quality DESC