MySQL说：文档1005-无法创建表'music'。'track'（错误号：150“外键约束格式不正确”）

我检查过很多次了。怎么了？

你把外键拼错了

CREATE DATABASE music DEFAULT CHARACTER SET utf8;
CREATE TABLE Artist
(artist_id INTEGER NOT NULL AUTO_INCREMENT,
 name varchar(255),
 PRIMARY KEY(artist_id)
)
ENGINE = INNODB;
CREATE TABLE Album
(
album_id INTEGER NOT NULL AUTO_INCREMENT,
title varchar(255),
artist_id INTEGER,
PRIMARY KEY(album_id),
INDEX USING BTREE(title),
CONSTRAINT FOREIGN KEY (artist_id)
REFERENCES Artist(Artist_id)
ON DELETE CASCADE ON UPDATE CASCADE   
)
ENGINE = InnoDB;

CREATE TABLE Genre
(
genre_id INTEGER NOT NULL AUTO_INCREMENT,
name VARCHAR(255),
PRIMARY KEY(genre_id),
INDEX USING BTREE (name)
)
ENGINE = INNODB;

CREATE TABLE Track
(
track_id INTEGER NOT NULL AUTO_INCREMENT,
title VARCHAR(255),
len INTEGER,
rating INTEGER,
count INTEGER,
album_id INTEGER,
genre_id INTEGER,
PRIMARY KEY (track_id),
INDEX USING BTREE(title),

CONSTRAINT FOREIGN KEY (album_id) REFERENCES Album(albumn_id)
    ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT FOREIGN KEY(genre_id) REFERENCES Genre(genre_id)
)
ENGINE = INNODB;

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请编辑问题，并对代码使用适当的引号和缩进。谢谢！我错了！

albumn_id