外键就是引用自己的主键，如何删除表中数据

做BBS论坛时，只有一张表存储大模块与小模块，好像就是树状结构表。如何删除下面的一条数据。delete from t_edition where editionid=1;(我用这个删，但报错）大虾，请教一下，。
drop database bbs_test;
create database bbs_test;
use bbs_test;create table t_edition
(
    editionId int primary key auto_increment,
    name varchar(20),
    createDate date,
    information varchar(500),
    parentid int,
    constraint fk_id foreign key(parentid) references t_edition(editionId)
    on   update   no action
    on   delete  no action
);insert into t_edition values(null,'javaSE',now(),'欢迎大家进入JAVASE技术',1);
insert into t_edition values(null,'J2EE/JSP',now(),'欢迎大家进入J2EE技术',2);
insert into t_edition values(null,'数据库',now(),'欢迎大家进入数据库技术',3);

解决方案 »

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有些复杂。或者先把 parentid  清为空，再delete
或者直接把　foreign_key_checks　给ＯＦＦ掉。想不出其它方法了，看看论坛中其它朋友有没有什么好主意。
SET FOREIGN_KEY_CHECKS = 0;delete from t_edition where editionid=1;SET FOREIGN_KEY_CHECKS = 1;能想到的也只有把外键约束去掉
1.首先你的逻辑有点问题自己怎么是自己的parent 如果是最大的parent 你可以设置null
2.删除可以禁用外键
也可以将你的数据改了mysql> select * from t_edition;
+-----------+----------+------------+--------------------+----------+
| editionId | name     | createDate | information        | parentid |
+-----------+----------+------------+--------------------+----------+
|         2 | J2EE/JSP | 2009-09-04 | ?迎大家?入J2EE技?  |        2 |
|         3 | 数据?    | 2009-09-04 | ?迎大家?入数据?技? |        2 |
+-----------+----------+------------+--------------------+----------+
2 rows in set (0.00 sec)
mysql> update t_edition set parentid=null ;
Query OK, 1 row affected (0.03 sec)
Rows matched: 1  Changed: 1  Warnings: 0
mysql> delete from t_edition where parentid is null;
3.不能删除原因是因为你的parentid和editionId关联
创建个存储过程从最低界别的开始删去因为最低级别的没有儿子
而你先删除爷爷肯定不行了
....
mysql> select * from t_edition;
+-----------+----------+------------+------------------------+----------+
| editionId | name     | createDate | information            | parentid |
+-----------+----------+------------+------------------------+----------+
|         1 | javaSE   | 2009-09-04 | 欢迎大家进入JAVASE技术 |        1 |
|         2 | J2EE/JSP | 2009-09-04 | 欢迎大家进入J2EE技术   |        2 |
|         3 | 数据库   | 2009-09-04 | 欢迎大家进入数据库技术 |        3 |
+-----------+----------+------------+------------------------+----------+
3 rows in set (0.00 sec)mysql> delete from t_edition where editionid=1;
ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constrai
nt fails (`csdn`.`t_edition`, CONSTRAINT `fk_id` FOREIGN KEY (`parentid`) REFERE
NCES `t_edition` (`editionId`) ON DELETE NO ACTION ON UPDATE NO ACTION)
mysql> select * from t_edition;
+-----------+----------+------------+------------------------+----------+
| editionId | name     | createDate | information            | parentid |
+-----------+----------+------------+------------------------+----------+
|         1 | javaSE   | 2009-09-04 | 欢迎大家进入JAVASE技术 |        1 |
|         2 | J2EE/JSP | 2009-09-04 | 欢迎大家进入J2EE技术   |        2 |
|         3 | 数据库   | 2009-09-04 | 欢迎大家进入数据库技术 |        3 |
+-----------+----------+------------+------------------------+----------+
3 rows in set (0.00 sec)mysql> update t_edition set parentid=null where editionid=1;
Query OK, 1 row affected (0.06 sec)
Rows matched: 1  Changed: 1  Warnings: 0mysql> select * from t_edition;
+-----------+----------+------------+------------------------+----------+
| editionId | name     | createDate | information            | parentid |
+-----------+----------+------------+------------------------+----------+
|         1 | javaSE   | 2009-09-04 | 欢迎大家进入JAVASE技术 |     NULL |
|         2 | J2EE/JSP | 2009-09-04 | 欢迎大家进入J2EE技术   |        2 |
|         3 | 数据库   | 2009-09-04 | 欢迎大家进入数据库技术 |        3 |
+-----------+----------+------------+------------------------+----------+
3 rows in set (0.00 sec)mysql> delete from t_edition where editionid=1;
Query OK, 1 row affected (0.06 sec)mysql> select * from t_edition;
+-----------+----------+------------+------------------------+----------+
| editionId | name     | createDate | information            | parentid |
+-----------+----------+------------+------------------------+----------+
|         2 | J2EE/JSP | 2009-09-04 | 欢迎大家进入J2EE技术   |        2 |
|         3 | 数据库   | 2009-09-04 | 欢迎大家进入数据库技术 |        3 |
+-----------+----------+------------+------------------------+----------+
2 rows in set (0.00 sec)mysql>
mysql> delete from t_edition where editionid=2;
ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constrai
nt fails (`csdn`.`t_edition`, CONSTRAINT `fk_id` FOREIGN KEY (`parentid`) REFERE
NCES `t_edition` (`editionId`) ON DELETE NO ACTION ON UPDATE NO ACTION)
mysql> set foreign_key_checks=0;
Query OK, 0 rows affected (0.00 sec)mysql> delete from t_edition where editionid=2;
Query OK, 1 row affected (0.06 sec)mysql> select * from t_edition;
+-----------+--------+------------+------------------------+----------+
| editionId | name   | createDate | information            | parentid |
+-----------+--------+------------+------------------------+----------+
|         3 | 数据库 | 2009-09-04 | 欢迎大家进入数据库技术 |        3 |
+-----------+--------+------------+------------------------+----------+
1 row in set (0.00 sec)mysql>
版主，这样会删多数据啊
“把　foreign_key_checks　给ＯＦＦ掉”，我用3楼那种做法测试貌似没有问题