多对多关系的 CREATE TABLE 上的 MySQL 错误

Question

我对简单的 CREATE TABLE 查询有疑问。我在多对多关系中有两个表“‘resort’(带有 resortID 和 resortName)和‘season’(带有 resortID 和 resortName)。 我正在尝试使用以下两个查询之一创建连接表 resort_season:

CREATE TABLE resort_season (
resortID MEDIUMINT UNSIGNED NOT NULL,
seasonID MEDIUMINT UNSIGNED NOT NULL,
FOREIGN KEY (resortID) REFERENCES resort (resortID),
FOREIGN KEY (seasonID) REFERENCES season (seasonID),
PRIMARY KEY (resortID, seasonID) NOT NULL
);

CREATE TABLE resort_season (
resortID MEDIUMINT UNSIGNED NOT NULL FOREIGN KEY REFERENCES resort (resortID),
seasonID MEDIUMINT UNSIGNED NOT NULL FOREIGN KEY REFERENCES season (seasonID),
PRIMARY KEY (resortID, seasonID) NOT NULL
);

两个查询都给我一个错误，内容如下(在本例中是第二个查询): “您的语法有误；请查看手册……在第 2 行的‘FOREIGN KEY REFERENCES resort (resortID), seasonID MEDIUMINT UNSIGNED NOT NULL F’附近使用正确的语法”。

我做错了什么？这让我很头疼，因为我看不出错误的原因。

如果我简单地做

CREATE TABLE resort_season (
resortID MEDIUMINT UNSIGNED NOT NULL,
seasonID MEDIUMINT UNSIGNED NOT NULL,
PRIMARY KEY (resortID, seasonID) NOT NULL
);

然后它工作正常并创建了表。不过，我不确定这张表是否会有效地引用表格度假村和季节。

Answer 1

从主键定义中删除 NOT NULL -

CREATE TABLE resort_season(
  resortID MEDIUMINT UNSIGNED NOT NULL,
  seasonID MEDIUMINT UNSIGNED NOT NULL,
  FOREIGN KEY (resortID) REFERENCES resort (resortID),
  FOREIGN KEY (seasonID) REFERENCES season (seasonID),
  PRIMARY KEY (resortID, seasonID)
);