mysql - 尝试使用外键创建表时出现错误 1005

Question

我正在尝试创建一些代表梦幻足球联赛的表格，该联赛本身包含球队，其本身包含精选的球员，这些球员是具有统计数据的球员。我现在有一个非常基本的草稿，我正在尝试让我的外键正常工作，但是，当我尝试添加 key 时，我不断收到此错误:

ERROR 1005 (HY000) at line 19: Can't create table 'football_db.PickedPlayers' (errno: 150)

我当然用谷歌搜索了一下，正如错误消息所示，问题与我在该表上的外键有关。

我可以不添加多组外键吗？或者是我选择的外键类型？提前致谢。

CREATE TABLE football_db.Leagues
    (league_id INT NOT NULL,
     league_name VARCHAR(100),
     PRIMARY KEY (league_id))
    ENGINE=INNODB;
CREATE TABLE football_db.Teams
    (league_id INT NOT NULL,
     team_id INT NOT NULL,
     team_name VARCHAR(100),
     PRIMARY KEY (league_id,team_id),
     FOREIGN KEY (league_id) REFERENCES Leagues(league_id))
    ENGINE=INNODB;
CREATE TABLE football_db.PickedPlayers
    (league_id INT NOT NULL,
     team_id INT NOT NULL,
     player_id INT NOT NULL,
     PRIMARY KEY (player_id),
     FOREIGN KEY (league_id,team_id) REFERENCES Teams(league_id,team_id),
     FOREIGN KEY (player_id) REFERENCES Players(player_id))
    ENGINE=INNODB;
CREATE TABLE football_db.Players
    (player_id INT NOT NULL,
     player_name VARCHAR(50),
     position VARCHAR(10),
     is_free_agent BOOL,
     PRIMARY KEY (player_id))
    ENGINE=INNODB;

Answer 1

在创建此表之前，您要引用表players，只需将创建表CREATE TABLE Football_db.PickedPlayers移动到最后一个位置，如下所示:

 CREATE TABLE Leagues
(league_id INT NOT NULL,
 league_name VARCHAR(100),
 PRIMARY KEY (league_id))
ENGINE=INNODB;
CREATE TABLE Teams
(league_id INT NOT NULL,
 team_id INT NOT NULL,
 team_name VARCHAR(100),
 PRIMARY KEY (league_id,team_id),
 FOREIGN KEY (league_id) REFERENCES Leagues(league_id))
ENGINE=INNODB;
CREATE TABLE Players
(player_id INT NOT NULL,
 player_name VARCHAR(50),
 position VARCHAR(10),
 is_free_agent BOOL,
 PRIMARY KEY (player_id))
ENGINE=INNODB;
CREATE TABLE PickedPlayers
(league_id INT NOT NULL,
 team_id INT NOT NULL,
 player_id INT NOT NULL,
 PRIMARY KEY (player_id),
 FOREIGN KEY (league_id,team_id) REFERENCES Teams(league_id,team_id),
 FOREIGN KEY (player_id) REFERENCES Players(player_id))
ENGINE=INNODB;

Live working demo