Question

CREATE TABLE location (
  uid int not null auto_increment primary key,
  name varchar(255) NOT NULL,
  `state_uid` int not null,
  FOREIGN KEY location(state_uid)
  REFERENCES state(uid)
  ON UPDATE CASCADE
  ON DELETE RESTRICT,
  `city_uid` int not null,
  FOREIGN KEY location(city_uid)
  REFERENCES city(uid)
  ON UPDATE CASCADE
  ON DELETE RESTRICT,
  `area_uid` int not null,
  FOREIGN KEY location(area_uid)
  REFERENCES area(uid)
  ON UPDATE CASCADE
  ON DELETE RESTRICT
);

Answer 1

CREATE TABLE location  (
  uid int not null auto_increment primary key,
  name varchar(255) NOT NULL,
  state_uid int not null, 
  city_uid int not null,
  area_uid int not null,

  CONSTRAINT fk_state FOREIGN KEY (state_uid)  REFERENCES state(uid)  ,
  CONSTRAINT fk_city  FOREIGN KEY (city_uid)  REFERENCES city(uid)  ,
  CONSTRAINT fk_area FOREIGN KEY (area_uid)  REFERENCES area(uid)   
);

尝试此查询

确保父表存在

Answer 2

你的版本几乎就好了。问题是外键引用中的location。

您对级联内容或列的排序没有任何问题。所以，这有效：

CREATE TABLE location (
  uid int not null auto_increment primary key,
  name varchar(255) NOT NULL,
  `state_uid` int not null,
  FOREIGN KEY (state_uid) REFERENCES state(uid) ON UPDATE CASCADE ON DELETE RESTRICT,
  `city_uid` int not null,
  FOREIGN KEY (city_uid) REFERENCES city(uid) ON UPDATE CASCADE ON DELETE RESTRICT,
  `area_uid` int not null,
  FOREIGN KEY (area_uid) REFERENCES area(uid) ON UPDATE CASCADE ON DELETE RESTRICT
);

Here是一个SQL小提琴。

请注意，在列定义之后放置显式foreign key（和其他约束）通常是传统的，没有规则或标准。实际上，大多数数据库都支持内联外键定义。但是，MySQL没有。

显示使用外键创建表的错误

2 个答案: