sqlite 查询每个流派中最畅销的专辑

Question

我正在使用基本的 chinook 数据库，但我不知道如何编写一个 SQLite 查询来为每个流派的畅销专辑创建一个名为 BestSeller 的视图（基于销售的曲目数量，命名为销售额），列为：流派、专辑、艺术家、销售额。

相册的架构 table：

 [Title] NVARCHAR(160)  NOT NULL,
 [ArtistId] INTEGER  NOT NULL,
 FOREIGN KEY ([ArtistId]) REFERENCES "artists" ([ArtistId])

艺术家 table :

[ArtistId] INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
[Name] NVARCHAR(120)

跟踪 table 架构：

 [TrackId] INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
    [Name] NVARCHAR(200)  NOT NULL,
    [AlbumId] INTEGER,
    [MediaTypeId] INTEGER  NOT NULL,
    [GenreId] INTEGER,
    [Composer] NVARCHAR(220),
    [Milliseconds] INTEGER  NOT NULL,
    [Bytes] INTEGER,
    [UnitPrice] NUMERIC(10,2)  NOT NULL,
    FOREIGN KEY ([AlbumId]) REFERENCES "albums" ([AlbumId])
                ON DELETE NO ACTION ON UPDATE NO ACTION,
    FOREIGN KEY ([GenreId]) REFERENCES "genres" ([GenreId])
                ON DELETE NO ACTION ON UPDATE NO ACTION,
    FOREIGN KEY ([MediaTypeId]) REFERENCES "media_types" ([MediaTypeId])
                ON DELETE NO ACTION ON UPDATE NO ACTION

table invoice_items:


    [InvoiceLineId] INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
    [InvoiceId] INTEGER  NOT NULL,
    [TrackId] INTEGER  NOT NULL,
    [UnitPrice] NUMERIC(10,2)  NOT NULL,
    [Quantity] INTEGER  NOT NULL,
    FOREIGN KEY ([InvoiceId]) REFERENCES "invoices" ([InvoiceId])
                ON DELETE NO ACTION ON UPDATE NO ACTION,
    FOREIGN KEY ([TrackId]) REFERENCES "tracks" ([TrackId])
                ON DELETE NO ACTION ON UPDATE NO ACTION

我还有所有其他 table。

albums          employees       invoices        playlists
artists         genres          media_types     tracks
customers       invoice_items   playlist_track

感谢任何帮助。

Answer 1

加入相关表格，按流派和专辑分组，得到每张专辑的曲目销量。
然后使用FIRST_VALUE()和MAX()window函数得到每个流派销量最高的专辑和销量：

CREATE VIEW BestSeller AS
SELECT DISTINCT 
       g.Name Genre, 
       FIRST_VALUE(a.Title) OVER (PARTITION BY g.GenreId ORDER BY COUNT(*) DESC) Album, 
       FIRST_VALUE(r.Name) OVER (PARTITION BY g.GenreId ORDER BY COUNT(*) DESC) Artist, 
       MAX(COUNT(*)) OVER (PARTITION BY g.GenreId) Sales
FROM genres g
INNER JOIN tracks t ON t.GenreId = g.GenreId
INNER JOIN albums a ON a.AlbumId = t.AlbumId
INNER JOIN artists r ON r.ArtistId = a.ArtistId
INNER JOIN invoice_items i ON i.TrackId = t.TrackId
GROUP BY g.GenreId, a.AlbumId;

见demo

sqlite 查询每个流派中最畅销的专辑

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