mysql级联

[taksunm]

mysql> desc student;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| sid | int(11) | YES | | NULL | |
| name | varchar(10) | YES | | NULL | |
| tid | int(11) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

mysql> desc teacher;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| tid | int(11) | YES | | NULL | |
| tname | varchar(10) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
mysql> alter table student add foreign key (tid) references teacher(tid) on delete cascade;
ERROR 1005 (HY000): Can't create table '.\minshi\#sql-6f8_2.frm' (errno: 150)
是哪里错了？

[winit]

因为tid不是key，我在mysqlmanul上看了，下面的可以
CREATE TABLE parent (id INT NOT NULL,
PRIMARY KEY (id)
) ENGINE=INNODB;
CREATE TABLE child (id INT, parent_id INT,
INDEX par_ind (parent_id),
FOREIGN KEY (parent_id) REFERENCES parent(id)
ON DELETE CASCADE
) ENGINE=INNODB;
但是把 PRIMARY KEY (id) 删除之后就报错，和你的类似

[possibleonline]

参考下，不会错的
ALTER TABLE `order_`
ADD CONSTRAINT `FK_u_o` FOREIGN KEY (`uid`) REFERENCES `user` (`id`) ON DELETE CASCADE ON UPDATE CASCADE;

[Sou2012]

检查下