只有InnoDB类型的表才可以使用外键
CREATE TABLE person (
id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
name CHAR(60) NOT NULL,
PRIMARY KEY (id)
)type=innoDB;
CREATE TABLE shirt (
id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
style ENUM('t-shirt', 'polo', 'dress') NOT NULL,
color ENUM('red', 'blue', 'orange', 'white', 'black') NOT NULL,
owner SMALLINT UNSIGNED NOT NULL,
FOREIGN KEY (owner) REFERENCES PERSON(id)
ON DELETE CASCADE
ON UPDATE CASCADE,
PRIMARY KEY (id)
)type=innoDB;
然后打开MySQL Administrator终于看到 FOREIGN KEY有东西了，尝试手工删除后再用MySQL Administrator建立，成功：）
INSERT INTO person VALUES (NULL, 'Antonio Paz');
SELECT @last := LAST_INSERT_ID();
INSERT INTO shirt VALUES
(NULL, 'polo', 'blue', @last),
(NULL, 'dress', 'white', @last),
(NULL, 't-shirt', 'blue', @last);
INSERT INTO person VALUES (NULL, 'Lilliana Angelovska');
SELECT @last := LAST_INSERT_ID();
INSERT INTO shirt VALUES
(NULL, 'dress', 'orange', @last),
(NULL, 'polo', 'red', @last),
(NULL, 'dress', 'blue', @last),
(NULL, 't-shirt', 'white', @last);
SELECT * FROM person;
SELECT * FROM shirt;
测试UPDATE关联
UPDATE PERSON SET id=3 WHERE id=1;
SELECT * FROM shirt;
测试DELETE关键
DELETE FROM PERSON WHERE id=3;
SELECT * FROM shirt;
看到有文章简单使用owner SMALLINT UNSIGNED NOT NULL REFERENCES person(id),进行连接，但这样的连接好像没任何意义，担看到“MySQL 3.23.7-alpha手册”有这样一句话“一些应用程序要求他们存在”或者“插入强制约束”、“级联删除”、“级联更新”这些特性是在MySQL甘个版本中才有吧
还有有文章说要建立INDEX (owner) 才可以，但我经测试并不需要，这可能是和MYSQL版本不同有关，我用的是MySQL4.1
PS.查看Mysql手册才知道从MySQL 4.1.2开始会自动建立这个INDEX (owner)
参考：
http://dev.mysql.com/doc/mysql/e ... ey-constraints.html
