Mysql外键用法是Mysql数据库中的基础知识，下面就为您详细将介绍Mysql外键用法，如果您对此方面有兴趣的话，不妨一看。
昨晚用Mysql建外键约束，始终没有成功，今天找到这个，原来只有InnoDB类型的表才可以使用Mysql外键.
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;